Molybdenum composite hybrid laminates and methods

ABSTRACT

In an embodiment of the disclosure, there is provided a molybdenum composite hybrid laminate. The laminate has a plurality of composite material layers. The laminate further has a plurality of surface treated molybdenum foil layers interweaved between the composite material layers. The laminate further has a plurality of adhesive layers disposed between and bonding adjacent layers of the composite material layers and the molybdenum foil layers.

REFERENCE TO GOVERNMENT CONTRACT

This invention was made with Government support under Contract No.HR0011-10-2-0001 awarded by Defense Advanced Research Program Agency(DARPA) Defense Science Office and the United States Navy. Thegovernment has certain rights in the invention.

BACKGROUND

1) Field of the Disclosure

The disclosure relates generally to composite materials and methods, andmore particularly, to hybrid composite laminates and methods for use incomposite structures, such as aircraft, spacecraft, and other vehicles.

2) Description of Related Art

Composite structures and component parts are used in a wide variety ofapplications, including in the manufacture of aircraft, spacecraft,rotorcraft, watercraft, automobiles, trucks, and other vehicles. Inparticular, in aircraft construction, composite structures and componentparts are used in increasing quantities to form the fuselage, wings,tail section, skin panels, and other component parts of the aircraft.

Known methods exist for fabricating hybrid laminates that combinepolymeric composite materials, such as graphite, boron, or a blend ofgraphite and boron composite, and metal foil materials, such as,titanium. The metal foil material may be added between laid up plies ofpolymeric composite unidirectional tape. For example, U.S. Pat. No.5,866,272 to Westre et al., incorporated by this reference, is one ofseveral patents teaching the placement of titanium foil between plies ofpolymeric composite unidirectional tape.

However, known composite and hybrid laminate materials can only leveragethe strengthening fibers that are in the load path and do not leveragethe strength of off-axis fibers. Moreover, known composite and hybridlaminate materials may not be effective at providing a currentdissipation path in the composite structure, for example, for effectivelightning strike protection. In addition, known composite and hybridlaminate materials may not provide effective impact resistance from highimpact sources, such as hail or bird strikes, without having to changethe structure by cross stitching or increasing the thickness of thecomposite structure, to name a few methods. Further, known composite andhybrid laminate materials may not provide effective thermal impingementresistance from high energy thermal impingement sources, such as lasersand X-rays. In addition, known composite and hybrid laminate materialsmay not provide the ability to combine separate structural andelectrical systems into a single system on an aircraft.

Moreover, lightweight composite designs, such as for keel beams inaircraft, may require additional structurally parasitic conductors toeffectively disperse the current from a lightning strike. Suchadditional conductors can add weight to the aircraft, and can result inincreased fuel costs and overall costs. Known composite and hybridlaminate materials may not provide the desired lightweight, highperforming composite keel beam that may be effective in conductingcurrent and acting as a lightning strike current return path.

In addition, when system penetrations, access paths, and other non-loadbearing areas are needed in composite or hybrid composite panels orstructures, it may be necessary to pad-up the lay-up to facilitate thetransmission of load around these areas. Known composite and hybridlaminate materials may be utilized to provide extra thickness which mayresult in additional cost, part volume and weight to the compositestructure.

Moreover, thermal and temperature uniformity and the ability to controlexcessive thermal energy due to cure kinetics of the resins areimportant fabrication issues when curing thermosetting composites.Thermal and temperature control of the curing cycle may preclude the useof some composite configurations.

Further, repair areas of composite structures may need a significantincrease in thickness of the composite structure to restore thecomposite structure to at least its original strength. This may causeadditional aerodynamic drag and may also affect the appearance of thecomposite structure.

Further, during fabrication of composite parts, the plies of an uncuredcomposite part having a uniform cross section may wrinkle at one or moreareas where a cured or pre-cured composite part having a non-uniformcross section is joined to the uncured composite part. Such wrinkling ofthe plies may be due to differences in pressure between the cured orpre-cured composite part and the uncured composite part at the joinedareas. Such wrinkling of the plies may result in fiber distortion of thecomposite material in the uncured composite part.

Finally, determination of initiation and propagation of flaws incomposite structures is important in predicting service life andmaintenance of the composite structure. Known composite and hybridlaminate structures are typically replaced or repaired at certainintervals. Such intervals are by their nature conservative, which maylead to additional, potentially unnecessary, cost accrual.

Accordingly, there is a need in the art for hybrid composite laminatesand methods that provide advantages over known composite materials andknown hybrid composite laminates and methods.

SUMMARY

This need for hybrid composite laminates and methods is satisfied. Asdiscussed in the below detailed description, embodiments of themolybdenum composite hybrid laminates and methods may providesignificant advantages over existing laminate materials, methods, andsystems.

In an embodiment of the disclosure, there is provided a molybdenumcomposite hybrid laminate. The laminate comprises a plurality ofcomposite material layers. The laminate further comprises a plurality ofsurface treated molybdenum foil layers interweaved between the compositematerial layers. The laminate further comprises a plurality of adhesivelayers disposed between and bonding adjacent layers of the compositematerial layers and the molybdenum foil layers.

In another embodiment of the disclosure, there is provided a molybdenumlaminate lay up. The molybdenum laminate lay up comprises a plurality ofcomposite material layers. The molybdenum laminate lay up furthercomprises a plurality of molybdenum foil containing layers interweavedbetween the composite material layers. Each molybdenum foil containinglayer comprises a composite material layer having a cutout portion of asurface treated molybdenum foil. The molybdenum laminate lay up furthercomprises a plurality of adhesive layers disposed between and bondingadjacent layers of the composite material layers and the molybdenum foilcontaining layers.

In another embodiment of the disclosure, there is provided a method offorming a molybdenum composite hybrid laminate. The method comprisestreating a surface of each of a plurality of molybdenum foil layers. Themethod further comprises interweaving the surface treated molybdenumfoil layers with a plurality of composite material layers. The methodfurther comprises bonding with an adhesive layer each of the surfacetreated molybdenum foil layers to adjacent composite material layers toform a molybdenum composite hybrid laminate having improved yieldstrength.

In another embodiment of the disclosure, there is provided a system formonitoring structural health of a composite structure. The systemcomprises a composite structure comprising one or more molybdenumcomposite hybrid laminates. Each laminate comprises a plurality ofcomposite material layers. The laminate further comprises a plurality ofsurface treated molybdenum foil layers interweaved between the compositematerial layers. The laminate further comprises a plurality of adhesivelayers disposed between and bonding adjacent layers of the compositematerial layers and the molybdenum foil layers. The system furthercomprises one or more electrical sensor devices coupled to the one ormore laminates. The sensor devices drive electrical current through themolybdenum foil layers and monitor any changes in flow of the electricalcurrent through the molybdenum foil layers in order to obtain structuralhealth data of the composite structure via one or more signals from theone or more electrical sensor devices.

In another embodiment of the disclosure, there is provided a method formonitoring structural health of a composite structure using molybdenumfoil layers. The method comprises treating a surface of each of aplurality of molybdenum foil layers. The method further comprisesinterweaving the surface treated molybdenum foil layers with a pluralityof composite material layers. The method further comprises bonding withan adhesive layer each of the surface treated molybdenum foil layers toadjacent composite material layers to form a molybdenum composite hybridlaminate having improved yield strength. The method further comprisescoupling one or more electrical sensor devices to the one or morelaminates. The method further comprises driving electrical currentthrough the molybdenum foil layers with the one or more electricalsensor devices. The method further comprises monitoring any change inflow of the electrical current through the molybdenum foil layers withthe one or more electrical sensor devices. The method further comprisesobtaining structural health data of the composite structure via one ormore signals from the one or more electrical sensor devices.

In another embodiment there is provided a method of fabricating anelectrical bus into an aircraft structure using molybdenum foil layers.The method comprises treating a surface of each of a plurality ofmolybdenum foil layers. The method further comprises interweaving thesurface treated molybdenum foil layers with a plurality of compositematerial layers, the molybdenum foil layers acting as an electrical bus.The method further comprises bonding with an adhesive layer each of thesurface treated molybdenum foil layers to adjacent composite materiallayers to form a molybdenum composite hybrid laminate having improvedyield strength. The method further comprises fabricating the electricalbus of the molybdenum composite hybrid laminate into an aircraftstructure.

In another embodiment there is provided a method of fabricating into anaircraft structure an aircraft composite keel beam for dispersingelectrical current from a lightning strike, the method using molybdenumfoil layers. The method comprises treating a surface of each of aplurality of molybdenum foil layers. The method further comprisesinterweaving the surface treated molybdenum foil layers with a pluralityof composite material layers, the molybdenum foil layers being anaircraft composite keel beam and current return path dispersingelectrical current from a lightning strike to an aircraft structure. Themethod further comprises bonding with an adhesive layer each of thesurface treated molybdenum foil layers to adjacent composite materiallayers to form a molybdenum composite hybrid laminate having improvedyield strength. The method further comprises using the molybdenumcomposite hybrid laminate in the aircraft structure to disperseelectrical current from the lightning strike to the aircraft structure.

In another embodiment there is provided a method of improving lightningattenuation of a composite structure using molybdenum foil layers. Themethod comprises treating a surface of each of a plurality of molybdenumfoil layers. The method further comprises interweaving the surfacetreated molybdenum foil layers with a plurality of composite materiallayers, the molybdenum foil layers being electrical energy dissipationpaths improving lightning attenuation of a composite structure. Themethod further comprises bonding with an adhesive layer each of thesurface treated molybdenum foil layers to adjacent composite materiallayers to form a molybdenum composite hybrid laminate having improvedyield strength. The method further comprises using the molybdenumcomposite hybrid laminate in the composite structure to improvelightning attenuation of the composite structure.

In another embodiment there is provided a method of improving thermalimpingement resistance of a composite structure using molybdenum foillayers. The method comprises treating a surface of each of a pluralityof molybdenum foil layers. The method further comprises interweaving thesurface treated molybdenum foil layers with a plurality of compositematerial layers, the molybdenum foil layers being thermal penetrationbarriers and thermal energy dissipation paths improving thermalimpingement resistance of a composite structure. The method furthercomprises bonding with an adhesive layer each of the surface treatedmolybdenum foil layers to adjacent composite material layers to form amolybdenum composite hybrid laminate having improved yield strength. Themethod further comprises using the molybdenum composite hybrid laminatein the composite structure to improve thermal impingement resistance ofthe composite structure.

In another embodiment there is provided a method of improving a curecycle of a composite structure using molybdenum foil layers. The methodcomprises treating a surface of each of a plurality of molybdenum foillayers. The method further comprises interweaving the surface treatedmolybdenum foil layers with a plurality of composite material layers,the molybdenum foil layers being thermal and temperature controllersimproving a cure cycle of a composite structure. The method furthercomprises bonding with an adhesive layer each of the surface treatedmolybdenum foil layers to adjacent composite material layers to form amolybdenum composite hybrid laminate having improved yield strength. Themethod further comprises using the molybdenum composite hybrid laminatein the composite structure to improve the cure cycle of the compositestructure.

In another embodiment there is provided a method of improving impactdurability of a composite structure using molybdenum foil layers. Themethod comprises treating a surface of each of a plurality of molybdenumfoil layers. The method further comprises interweaving the surfacetreated molybdenum foil layers with a plurality of composite materiallayers, the molybdenum foil layers being load dissipation pathsimproving impact durability of a composite structure. The method furthercomprises bonding with an adhesive layer each of the surface treatedmolybdenum foil layers to adjacent composite material layers to form amolybdenum composite hybrid laminate having improved yield strength. Themethod further comprises using the molybdenum composite hybrid laminatein the composite structure to improve impact durability of the compositestructure.

In another embodiment there is provided a method of steering load aroundnon-load bearing areas in a composite structure using molybdenum foillayers. The method comprises treating a surface of each of a pluralityof molybdenum foil layers. The method further comprises interweaving thesurface treated molybdenum foil layers with a plurality of compositematerial layers, the molybdenum foil layers being load steering pathssteering load around non-load bearing areas in a composite structure.The method further comprises bonding with an adhesive layer each of thesurface treated molybdenum foil layers to adjacent composite materiallayers to form a molybdenum composite hybrid laminate having improvedyield strength. The method further comprises using the molybdenumcomposite hybrid laminate in the composite structure to steer loadaround the non-load bearing areas in the composite structure.

In another embodiment there is provided a method of reinforcing anddrawing load away from a repair area in a composite structure usingmolybdenum foil layers. The method comprises treating a surface of eachof a plurality of molybdenum foil layers. The method further comprisesinterweaving the surface treated molybdenum foil layers with a pluralityof composite material layers, the molybdenum foil layers beingreinforcement elements and load drawing paths reinforcing and drawingload away from a repair area in a composite structure. The methodfurther comprises bonding with an adhesive layer each of the surfacetreated molybdenum foil layers to adjacent composite material layers toform a molybdenum composite hybrid laminate having improved yieldstrength. The method further comprises using the molybdenum compositehybrid laminate in the composite structure to reinforce and draw loadaway from the repair area in the composite structure.

In another embodiment there is provided a method of mitigating fiberdistortion in a composite structure using molybdenum foil layers. Themethod comprises treating a surface of each of a plurality of molybdenumfoil layers. The method further comprises interweaving the surfacetreated molybdenum foil layers with a plurality of composite materiallayers, the molybdenum foil layers being fiber stabilizers mitigatingfiber distortion in a composite structure. The method further comprisesbonding with an adhesive layer each of the surface treated molybdenumfoil layers to adjacent composite material layers to form a molybdenumcomposite hybrid laminate having improved yield strength. The methodfurther comprises using the molybdenum composite hybrid laminate in thecomposite structure to mitigate fiber distortion in the compositestructure.

The features, functions, and advantages that have been discussed can beachieved independently in various embodiments of the disclosure or maybe combined in yet other embodiments further details of which can beseen with reference to the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be better understood with reference to the followingdetailed description taken in conjunction with the accompanying drawingswhich illustrate preferred and exemplary embodiments, but which are notnecessarily drawn to scale, wherein:

FIG. 1 is an illustration of a perspective view of an aircraft which mayincorporate one or more advantageous embodiments of a molybdenumcomposite hybrid laminate of the disclosure;

FIG. 2 is an illustration of a flow diagram of an aircraft productionand service methodology;

FIG. 3 is an illustration of a functional block diagram of an aircraft;

FIG. 4 is an illustration of a functional block diagram of one of theembodiments of a molybdenum composite hybrid laminate the disclosure;

FIG. 5 is an illustration of an isometric partial sectional view of oneof the embodiments of a molybdenum laminate lay up of the disclosure;

FIG. 6 is a side cross-sectional view of another one of the embodimentsof a molybdenum laminate lay up of the disclosure;

FIG. 7 is an illustration of a schematic diagram of off-axis fibersleveraged through Poisson's effects in the surface treated molybdenumfoil layer;

FIG. 8 is an illustration of a schematic diagram of one of theembodiments of a molybdenum composite hybrid laminate of the disclosurewhere the molybdenum foil layers act as an electrical bus;

FIG. 9 is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate of the disclosurewhere the molybdenum foil layers act as electrical energy dissipationpaths for improved lightning attenuation;

FIG. 10 is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate of the disclosurewhere the molybdenum foil layers act as thermal penetration barriers andthermal energy dissipation paths for improved thermal impingementresistance;

FIG. 11 is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate of the disclosurewhere the molybdenum foil layers act as load dissipation paths forimproved impact durability;

FIG. 12A is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate of the disclosurewhere the molybdenum foil layers act as load steering paths for non-loadbearing areas;

FIG. 12B is an illustration of a schematic diagram of a cross-sectiontaken at lines 12B-12B of FIG. 12A;

FIG. 13 is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate of the disclosurewhere the molybdenum foil layers act as thermal and temperaturecontrollers for improving a cure cycle;

FIG. 14A is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate of the disclosurewhere the molybdenum foil layers act as reinforcement elements and loaddrawing paths for a patch repair area;

FIG. 14B is an illustration of a schematic diagram of a cross-sectiontaken at lines 14B-14B of FIG. 14A;

FIG. 14C is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate of the disclosurewhere the molybdenum foil layers act as reinforcement elements and loaddrawing paths for a scarf repair area;

FIG. 14D is an illustration of a schematic diagram of a cross-sectiontaken at lines 14D-14D of FIG. 14C;

FIG. 15 is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate of the disclosurewhere the molybdenum foil layers act as an aircraft composite keel beamand current return paths for dispersing electrical current fromlightning strikes;

FIG. 16 is an illustration of a functional block diagram of one of theexemplary embodiments of a system for monitoring structural health of acomposite structure of the disclosure;

FIG. 17 is an illustration of a schematic diagram of a compositestructure having areas of fiber distortion;

FIG. 18 is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate of the disclosurewhere the molybdenum foil layers act as fiber stabilizers; and,

FIGS. 19-29 are flow diagrams illustrating exemplary embodiments ofmethods of the disclosure.

DETAILED DESCRIPTION

Disclosed embodiments will now be described more fully hereinafter withreference to the accompanying drawings, in which some, but not all ofthe disclosed embodiments are shown. Indeed, several differentembodiments may be provided and should not be construed as limited tothe embodiments set forth herein. Rather, these embodiments are providedso that this disclosure will be thorough and complete and will fullyconvey the scope of the disclosure to those skilled in the art.

Now referring to the Figures, FIG. 1 is an illustration of a perspectiveview of an exemplary aircraft structure 10 which may incorporate one ormore advantageous embodiments of a molybdenum composite hybrid laminate100 (see FIG. 4) of the disclosure. As shown in FIG. 1, the aircraftstructure 10 comprises a fuselage 12, a nose 14, a cockpit 16, wings 18operatively coupled to the fuselage 12, one or more propulsion units 20,a tail vertical stabilizer 22, one or more tail horizontal stabilizers24, and one or more keel beams 26. The aircraft 10 structure may be madefrom composite and/or metallic materials that may be used on suchportions of the aircraft structure 10, including but not limited to, thefuselage 12, the nose 14, the wings 18, the tail vertical stabilizer 22,the one or more tail horizontal stabilizers 24, and the one or more keelbeams 26. Although the aircraft 10 shown in FIG. 1 is generallyrepresentative of a commercial passenger aircraft, the molybdenumcomposite hybrid laminate 100, as disclosed herein, may also be employedin other types of aircraft. More specifically, the teachings of thedisclosed embodiments may be applied to other passenger aircraft, cargoaircraft, military aircraft, rotorcraft, and other types of aircraft oraerial vehicles, as well as aerospace vehicles, satellites, space launchvehicles, rockets, and other aerospace vehicles. It may also beappreciated that embodiments of methods, systems, and apparatuses inaccordance with the disclosure may be utilized in other vehicles, suchas boats and other watercraft, trains, automobiles, trucks, and buses.

FIG. 2 is an illustration of a flow diagram of an aircraft productionand service methodology 30. FIG. 3 is an illustration of a functionalblock diagram of an aircraft 50. Referring to FIGS. 2-3, embodiments ofthe disclosure may be described in the context of the aircraftmanufacturing and service method 30 as shown in FIG. 2 and the aircraft50 as shown in FIG. 3. During pre-production, exemplary method 30 mayinclude specification and design 32 of the aircraft 50 and materialprocurement 34. During production, component and subassemblymanufacturing 36 and system integration 38 of the aircraft 50 takesplace. Thereafter, the aircraft 50 may go through certification anddelivery 40 in order to be placed in service 42. While in service 42 bya customer, the aircraft 50 is scheduled for routine maintenance andservice 44 (which may also include modification, reconfiguration,refurbishment, and so on).

Each of the processes of method 30 may be performed or carried out by asystem integrator, a third party, and/or an operator (e.g., a customer).For the purposes of this description, a system integrator may includewithout limitation any number of aircraft manufacturers and major-systemsubcontractors; a third party may include without limitation any numberof vendors, subcontractors, and suppliers; and an operator may be anairline, leasing company, military entity, service organization, and soon.

As shown in FIG. 3, the aircraft 50 produced by exemplary method 30 mayinclude an airframe 52 with a plurality of systems 54 and an interior56. The airframe 52 may incorporate one or more advantageous embodimentsof the molybdenum composite hybrid laminate 100 (see FIG. 4) of thedisclosure. Examples of high-level systems 54 include one or more of apropulsion system 58, an electrical system 60, a hydraulic system 62,and an environmental system 64. Any number of other systems may beincluded. Although an aerospace example is shown, the principles of theinvention may be applied to other industries, such as the automotiveindustry.

Apparatus and methods embodied herein may be employed during any one ormore of the stages of the production and service method 30. For example,components or subassemblies corresponding to production process 36 maybe fabricated or manufactured in a manner similar to components orsubassemblies produced while the aircraft 50 is in service 42. Also, oneor more apparatus embodiments, method embodiments, or a combinationthereof may be utilized during the production stages 36 and 38, forexample, by substantially expediting assembly of or reducing the cost ofan aircraft 50. Similarly, one or more of apparatus embodiments, methodembodiments, or a combination thereof may be utilized while the aircraft50 is in service 42, for example and without limitation, to maintenanceand service 44.

FIG. 4 is an illustration of a functional block diagram of one of theembodiments of the molybdenum composite hybrid laminate 100 thedisclosure. As shown in FIG. 4, there is provided the molybdenumcomposite hybrid laminate 100 to improve yield strength 102 of acomposite structure 104. The molybdenum composite hybrid laminate 100comprises a plurality of composite material layers 106. Each of thecomposite material layers 106 comprises a fiber-reinforced polymericmaterial 108. The fiber-reinforced polymeric material 108 preferablycomprises off-axis fibers 110 (see FIG. 7) and substantially parallelfibers 152 (see FIG. 7) in a resin matrix 114 (see FIG. 7). The off-axisfibers 110 and substantially parallel fibers 152 preferably comprisehigh modulus strengthening fibers 112 disposed in the resin matrix 114.The high modulus strengthening fibers 112 may be made of a materialcomprising graphite, glass, carbon, boron, ceramics, aramids,polyolefins, polyethylenes, polymers, tungsten carbide, or othersuitable materials. The resin matrix 114 may be made of resin materialcomprising thermosetting resins such as epoxies and polyesters,thermoplastic resins such as polyamides, polyolefins and fluoropolymers,hybrid polymer resins with properties of both thermosetting resins andthermoplastic resins, or other suitable resin materials. The off-axisfibers 110 and substantially parallel fibers 152 preferably have a fibertensile strength 116 in a range of about 500 KSI (thousands of poundsper square inch) to about 1000 KSI. The off-axis fibers 110 andsubstantially parallel fibers 152 preferably have a fiber stiffness 118in a range of about 32 MSI (millions of pounds per square inch) to about100 MSI. The off-axis fibers 110 and substantially parallel fibers 152preferably have a fiber elongation 120 in a range of about 0.1% to about0.5% or greater of the original fiber length. Each composite materiallayer 106 preferably has a thickness in a range of from about 1 mil toabout 20 mils. More preferably, each composite material layer 106 has athickness in a range of from about 4 mils to about 8 mils.

The molybdenum composite hybrid laminate 100 further comprises aplurality of surface treated molybdenum foil layers 122 interweavedbetween the composite material layers 106. Each of the surface treatedmolybdenum foil layers 122 has a sufficient molybdenum stiffness 124 toleverage the fiber tensile strength 116 and the fiber stiffness 118 ofthe off-axis fibers 110 in adjacent composite material layers 106 viaPoisson's effects in the surface treated molybdenum foil layers 122. Forpurposes of this disclosure, “Poisson's effects” means the dual effectthat a compression load has on an object, that is, the compressioncauses the object to become shorter in the direction of the compressiveload and wider laterally. For each different type of material, there isa specific ratio of strain in the axial direction to strain in thetransverse direction, and this is referred to as the “Poisson ratio”.The molybdenum stiffness 124 comprises 47 MSI (millions of pounds persquare inch). The high molybdenum stiffness 124 of the surface treatedmolybdenum foil layer 122 allows the surface treated molybdenum foillayer 122 to leverage the fiber tensile strength 116 and the fiberstiffness 118 of the off-axis fibers 110 in the fiber-reinforcedpolymeric material 108 through Poisson's effects in the surface treatedmolybdenum foil layer 122 and prevents the off-axis fibers 110 andsubstantially parallel fibers 152 in the fiber-reinforced polymericmaterial 108 from buckling in compression.

FIG. 7 is an illustration of a schematic diagram of the off-axis fibers110 leveraged through Poisson's effects in the surface treatedmolybdenum foil layer 122. FIG. 7 shows the off-axis fibers 110comprising high modulus strengthening fibers 112 in the resin matrix 114and shows substantially parallel fibers 152 in the resin matrix 114 andin a direction D of a load path 154. The design of the molybdenumcomposite hybrid laminate 100 enables leveraging of the strength of boththe substantially parallel fibers 152 that run in a direction D of aload path 154, and the surface treated molybdenum foil layer 122 enablesleveraging of the fiber tensile strength 116 and the fiber stiffness 118of the off-axis fibers 110. In addition, the surface treated molybdenumfoil layer 122 may be constrained and may not act in a standardPoisson's effect manner. Moreover, a tri-axial loading state, that is, astate where there is significant stress being applied in all threedirections x, y, and z, exists in the surface treated molybdenum foillayer 122 to increase an actual yield point or yield strength of thesurface treated molybdenum foil layer 122 depending on the bond strengthof the surface treated molybdenum foil layer 122. Increasing the actualyield point or yield strength enables additional z bonding to be appliedto the molybdenum foil by the bond.

As shown in FIG. 4, each of the surface treated molybdenum foil layers122 further has a molybdenum strength 126. Preferably, the molybdenumstrength 126 is in a range of about 125 KSI (thousands of pounds persquare inch) to about 160 KSI. As shown in FIG. 4, each of the surfacetreated molybdenum foil layers 122 further has a molybdenum electricalconductivity 128. Preferably, the molybdenum electrical conductivity 128is about 17.9×10⁶ l/Ohm-m (Ohm-meter). As shown in FIG. 4, each of thesurface treated molybdenum foil layers 122 further has a molybdenumthermal conductivity 130. Preferably, the molybdenum thermalconductivity 130 is about 138 W m⁻¹ K⁻¹. (Watts per meter Kelvin). Asshown in FIG. 4, each of the surface treated molybdenum foil layers 122further has a molybdenum melting point 132. Each surface treatedmolybdenum foil layer 122 preferably has a thickness in a range of fromabout 1 mil to about 40 mil.

The surface treated molybdenum foil layers 122 are preferably surfacetreated to improve bonding between the surface treated molybdenum foillayer 122 interface with an adjacent composite material layer 106. Thesurface treated molybdenum foil layer 122 is preferably surface treatedvia one or more surface treatments comprising sol gel surface treatment,water based sol gel paint, grit blasting, sanding, sandblasting, solventwiping, abrading, chemical cleaning, chemical etching, laser ablation,or another suitable surface treatment. Useful surface treatmentprocesses are described, for example, in U.S. Pat. Nos. 3,959,091;3,989,876; 4,473,446; and, 6,037,060, all of which are incorporatedherein by reference.

The molybdenum composite hybrid laminate 100 further comprises aplurality of adhesive layers 134 disposed between and bonding adjacentlayers of the composite material layers 106 and the surface treatedmolybdenum foil layers 122. The adhesive layer 134 preferably comprisesan adhesive made of a material such as thermosetting epoxy resinadhesives, epoxy adhesives, thermoplastic adhesives, polyimideadhesives, bismaleimide adhesives, polyurethane adhesives, toughenedacrylic adhesives, or another suitable adhesive. Each adhesive layer 134preferably has a thickness in a range of from about 0.5 mil to about 2.0mil. Preferably, the adhesive layer 134 provides minimal adhesive to weta surface 125 a or 125 b (see FIG. 6) of the molybdenum foil layer 122to facilitate bonding with the adjacent composite material layer 106.

The molybdenum composite hybrid laminate 100 is used in a compositestructure 104 and improves yield strength 102 (see FIG. 4) in thecomposite structure 104. The composite structure 104 may comprise anaircraft structure 10 (see FIG. 1) or another suitable compositestructure. The molybdenum composite hybrid laminate 100 is preferablydesigned for low temperature applications, such as a temperature of lessthan about 500 degrees Fahrenheit. Exemplary low temperatureapplications may include use of the molybdenum composite hybrid laminate100 for subsonic aircraft skins and substructures located away from theone or more propulsion units 20 (see FIG. 1), such as the aircraft jetengines.

FIG. 5 is an illustration of an isometric partial sectional view of oneof the embodiments of a molybdenum laminate lay up 101 of thedisclosure. As shown in FIG. 5, the molybdenum laminate lay up 101comprises a plurality of composite material layers 106 and a pluralityof molybdenum foil containing layers 146 interweaved between thecomposite material layers 106. Each of the composite material layers106, as discussed in detail above, preferably comprises afiber-reinforced polymeric material 108. Each of the molybdenum foilcontaining layers 146 comprises a composite material layer 106,preferably comprising the fiber-reinforced polymeric material 108, wherethe composite material layer 106 may have a cutout portion 144 ofmolybdenum foil 123 that may be surface treated. As further shown inFIG. 5, the molybdenum laminate lay up 101 further comprises adhesivelayers 134 disposed between and bonding adjacent layers of the compositematerial layers 106 and the interfacing molybdenum foil containinglayers 146. The molybdenum laminate lay up 101 may further comprise oneor more surface treated molybdenum foil layers 122 adjacent one or morecomposite material layers 106 and/or adjacent one or more molybdenumfoil containing layers 146. As shown in FIG. 5, a surface treatedmolybdenum foil layer 122 is adjacent a composite material layer 106 andis bonded to the composite material layer 106 with an adhesive layer134.

As shown in FIG. 5, each lamina or ply 136 of the molybdenum laminatelay up 101 has a first face 138 and a second face 140 spaced apart andextending to a terminal edge 142. As further shown in FIG. 5, in areasof the molybdenum laminate lay up 101 requiring specific reinforcementwith the surface treated molybdenum foil 123, the cutout portion 144 maybe formed in the molybdenum foil containing layer 146. The cut-outportion 144 may be formed, for example, by removing the compositematerial layer 106 up to an interior edge 148 (see FIG. 5), or by layingup the composite material layer 106 up to the interior edge 148, leavingthe formed cutout portion 144. Suitable lay-up devices for forming thecutout portions 144 may comprise, for example, known contour tape layingmachines (CTLM) (not shown), such as those manufactured by CincinnatiMachine, Inc. of Cincinnati, Ohio. The molybdenum foil containing layer146 may then be completed with the surface treated molybdenum foil 123to substantially fill each cutout portion 144. The molybdenum foilcontaining layer 146 comprises the composite material layer 106 thatextends between the first face 138 and the second face 140 and has theinterior edge 148 defining the cutout portion 144. The molybdenum foilcontaining layer 146 further comprises the surface treated molybdenumfoil 123 that extends between the first face 138 and the second face 140substantially from the interior edge 148 filling the cutout portion 144.

As further shown in FIG. 5, where multiple molybdenum foil containinglayers 146 are to be interrupted, the interior edges 148 of the cutoutportions 144 may be staggered in order to prevent the overlay of two ormore interior edges 148 in order to provide improved load distributionby the surface treated molybdenum foil 123. The staggered interior edges148 of the cutout portions 144 may also minimize or eliminate possibleresin accumulation that may occur at the ends of the surface treatedmolybdenum foil 123. Interweaving surface treated molybdenum foil 123,as well as interrupting the composite material layer 106 in a singlemolybdenum foil containing layer 146 with the surface treated molybdenumfoil 123 in accordance with the disclosure may yield distinct propertiesin the resulting molybdenum laminate lay up 101.

FIG. 6 is a side cross-sectional view of another one of the embodimentsof a molybdenum laminate lay up 150 of the disclosure. As shown in FIG.6, the composite material layers 106 and the molybdenum foil containinglayers 146 may be oriented at angles of approximately −45 (minusforty-five) degrees, approximately +45 (plus forty-five) degrees,approximately 0 (zero) degrees, or approximately 90 (ninety) degrees inone particular embodiment. Each molybdenum foil containing layer 146comprises the composite material layer 106 having the cutout portion 144of surface treated molybdenum foil 123. With the molybdenum laminate layup 150, as well as the molybdenum laminate lay up 101 (see FIG. 5),preferably no two adjacent layers are oriented at the same angle, thatis, an adjacent composite material layer 106 and a molybdenum foilcontaining layer 146 are not orientated at the same angle, an adjacentcomposite material layer 106 and a surface treated molybdenum foil layer122 are not oriented at the same angle, and an adjacent molybdenum foilcontaining layer 146 and a surface treated molybdenum foil layer 122 arenot oriented at the same angle.

In another embodiment of the disclosure, there is provided a molybdenumcomposite hybrid laminate 100 having molybdenum foil layers 122 that actas an electrical bus 160 (see FIG. 8) in a composite structure 104 (seeFIG. 4), such as an aircraft structure 10 (see FIG. 1). FIG. 8 is anillustration of a schematic diagram of one of the embodiments of themolybdenum composite hybrid laminate 100 of the disclosure where thesurface treated molybdenum foil layers 122 act as the electrical bus160. For purposes of this application, an electrical bus means adistribution point in an aircraft electrical system from whichelectrical loads derive their power. The surface treated molybdenum foillayers 122 have a sufficient molybdenum electrical conductivity 128 (seeFIG. 4) to enable the surface treated molybdenum foil layers 122 to actas the electrical bus 160 for integrating separate structural andelectrical systems (not shown) into a single system 158 (see FIG. 8) forthe composite structure 104 (see FIG. 4), such as the aircraft structure10 (see FIG. 1), resulting in an overall reduced weight of the aircraftstructure 10.

As discussed above, the molybdenum composite hybrid laminate 100comprises a plurality of composite material layers 106 (see FIG. 8).Each composite material layer 106 comprises a fiber-reinforced polymericmaterial 108 (see FIG. 4). Preferably, the composite material layer 106comprises a graphite/resin based material layer 164 (see FIG. 8). Themolybdenum composite hybrid laminate 100 further comprises a pluralityof surface treated molybdenum foil layers 122 (see FIG. 8) interweavedbetween the composite material layers 106 (see FIG. 8). The surfacetreated molybdenum foil layers 122 have a sufficient molybdenumstiffness 124 (see FIG. 4) to leverage the fiber tensile strength 116(see FIG. 4) and the fiber stiffness 118 (see FIG. 4) of the off-axisfibers 110 (see FIG. 4) in adjacent composite material layers 106 viaPoisson's effects in the surface treated molybdenum foil layers 122. Themolybdenum composite hybrid laminate 100 laminate further comprises aplurality of adhesive layers 134 (see FIG. 8) disposed between andbonding adjacent layers of the composite material layers 106 and thesurface treated molybdenum foil layers 122.

In this embodiment, preferably, the surface treated molybdenum foillayers 122 are separate from each other and have sufficient molybdenumelectrical conductivity 128 (see FIG. 4) to enable the surface treatedmolybdenum foil layers 122 to perform as the electrical bus 160.Molybdenum is an excellent electrical conductor. It is this lowelectrical resistance characteristic that enables the surface treatedmolybdenum foil layers 122 to act as an excellent electrical bus for awide range of electrical applications on the composite structure 104(see FIG. 4), such as the aircraft structure 10 (see FIG. 1).Preferably, the molybdenum composite hybrid laminate 100 comprisesmultiple surface treated molybdenum foil layers 122 in the compositestructure 104, and thus, a number of discrete conductors may beavailable. Each of the surface treated molybdenum foil layers 122 maycomprise strips that are electrically separate from one another, andeach of these layers or strips can act as individual circuit legs 162(see FIG. 8) of a separate circuit. The adhesive layers 134 (see FIG. 8)may act as electrical insulation layers 166 (see FIG. 8) for the surfacetreated molybdenum foil layers 122 when separate circuits are desired.Electrical current (I) 170 (see FIG. 8) may be conducted by theindividual layers of the surface treated molybdenum foil layers 122, aselectrical current flow 172 (see FIG. 8) moves through the single system158 (see FIG. 8). This embodiment may integrate the electricalrequirements of the electrical system and the structural requirements ofthe structural system into the single system 158, resulting insignificant weight savings.

In another embodiment there is provided a method 430 of fabricating anelectrical bus 160 (see FIG. 8) into a composite structure 104 (see FIG.4), such as an aircraft structure 10 (see FIG. 1), using molybdenum foillayers 122 (see FIG. 8). FIG. 21 is a flow diagram illustrating one ofthe exemplary embodiments of the method 430 of fabricating theelectrical bus 160. The method 430 comprises step 432 of treating asurface 125 a or 125 b (see FIG. 6) of each of a plurality of molybdenumfoil layers 122. Treating the surface 125 a or 125 b of the molybdenumfoil layers 122 may comprise one or more surface treatments comprisingsol gel surface treatment, water based sol gel paint, grit blasting,sanding, sandblasting, solvent wiping, abrading, laser ablation,chemical cleaning, chemical etching, or another suitable surfacetreatment.

The method 430 further comprises step 434 of interweaving the surfacetreated molybdenum foil layers 122 with a plurality of compositematerial layers 106 (see FIG. 8). The molybdenum foil layers 122 act asan electrical bus 160 (see FIG. 8). The molybdenum foil layers 122 havea sufficient molybdenum stiffness 124 (see FIG. 4) to leverage a fibertensile strength 116 (see FIG. 4) and a fiber stiffness 118 (see FIG. 4)of off-axis fibers 110 (see FIG. 4) in adjacent composite materiallayers 106 via Poisson's effects in the molybdenum foil layers 122. Themolybdenum foil layers 122 are preferably separate from each other andfurther have a sufficient molybdenum electrical conductivity 128 (seeFIG. 4) to enable the molybdenum foil layers 122 to act as theelectrical bus 160 in the aircraft structure 10. The electrical bus 160may integrate separate structural and electrical systems into a singlesystem 158 (see FIG. 8) in the aircraft structure 10, thus resulting inan overall reduced weight of the aircraft structure 10.

The method 430 further comprises step 436 of bonding with an adhesivelayer 134 (see FIG. 8) each of the surface treated molybdenum foillayers 122 to adjacent composite material layers 106 to form amolybdenum composite hybrid laminate 100 (see FIG. 8) having improvedyield strength 102 (see FIG. 4). The interweaving step 434 and bondingstep 436 may further comprise one or more of compacting, consolidating,and curing the interweaved surface treated molybdenum foil layers 122and the composite material layers 106. The method 430 further comprisesstep 438 of fabricating the electrical bus 160 of the molybdenumcomposite hybrid laminate 100 into an aircraft structure 10.

In another embodiment of the disclosure, there is provided a system 250(see FIG. 16) for monitoring structural health of a composite structure104 (see FIG. 16). FIG. 16 is an illustration of a functional blockdiagram of one of the exemplary embodiments of the system 250 formonitoring structural health of the composite structure 104. As shown inFIG. 16, the system 250 comprises a composite structure 104, preferablyan aircraft 10 (see FIG. 1), comprising one or more molybdenum compositehybrid laminates 100. As shown in FIG. 16, each molybdenum compositehybrid laminate 100 comprises a plurality of composite material layers106, each composite material layer 106 comprising a fiber-reinforcedpolymeric material 108. As shown in FIG. 16, the molybdenum compositehybrid laminate 100 further comprises a plurality of surface treatedmolybdenum foil layers 122 interweaved between the composite materiallayers 106. The surface treated molybdenum foil layers 122 have asufficient molybdenum stiffness 124 (see FIG. 4) to leverage the fibertensile strength 116 (see FIG. 4) and the fiber stiffness (see FIG. 4)of the off-axis fibers 110 (see FIG. 4) in adjacent composite materiallayers 106 via Poisson's effects in the surface treated molybdenum foillayers 122. The surface treated molybdenum foil layers 122 are separatefrom each other and have a sufficient molybdenum electrical conductivity128 (see FIG. 4) to enable the surface treated molybdenum foil layers122 to perform as an electrical bus 160 (see FIG. 16). As shown in FIG.16, the molybdenum composite hybrid laminate 100 further comprises aplurality of adhesive layers 134 disposed between and bonding adjacentlayers of the composite material layers 106 and the surface treatedmolybdenum foil layers 122.

In this embodiment, as shown in FIG. 16, the system 250 furthercomprises one or more electrical sensor devices 168 coupled to one ormore of the molybdenum composite hybrid laminates 100. The electricalsensor devices 168 drive electrical current 170 (see FIG. 16) throughthe surface treated molybdenum foil layers 122 and monitor any changesin electrical current flow 172 (see FIG. 16) through the surface treatedmolybdenum foil layers 122 in order to obtain structural health data 254(see FIG. 16) of the composite structure 104 via one or more signals 252(see FIG. 16) from the one or more electrical sensor devices 168. Suchstructural health data 254 may comprise lightning strike detection,inception of structural flaws, propagation of structural flaws,potential deterioration, and actual deterioration, or other suitablestructural health data that may be detected via full or partialelectrical current interruption.

The molybdenum foil provides enhanced mechanical properties to thecomposite lay-ups. In addition, the high molybdenum electricalconductivity 128 enables the molybdenum to perform well as an electricalbus 160 (see FIG. 16). Each of the surface treated molybdenum foillayers 122 may comprise strips that are electrically separate from oneanother. Each of these layers or strips can act as individual circuitlegs 162 (see FIG. 16) of a separate circuit. In addition, theelectrical current 170 that flows in these circuits of surface treatedmolybdenum foil 122 may be monitored for evidence of any potentialdeterioration.

The resistance of each circuit of surface treated molybdenum foil 122may be monitored to provide evidence of sound structure. If theresistance or signal 252 changes, this may provide data about thesoundness of the composite structure 104. This information maypotentially allow greater useful life of the composite structure 104,such as an aircraft structure 10 (see FIG. 1), and greater in-servicetime for the aircraft structure 10 due to actual access to structuralhealth data 254 or information about the soundness of the compositestructure 104 instead of relying only on scheduled maintenance. Thesystem 250 enables less out-of-service time for the aircraft structure10 and enables refurbishment or repair of composite structures 104 whenneeded.

In another embodiment of the disclosure, there is provided a molybdenumcomposite hybrid laminate 100 (see FIG. 9) to improve lightning strike180 (see FIG. 9) attenuation or dissipation of a composite structure 104(see FIG. 4). FIG. 9 is an illustration of a schematic diagram ofanother one of the embodiments of the molybdenum composite hybridlaminate 100 of the disclosure where the surface treated molybdenum foillayers 122 act as electrical energy dissipation paths 186 improving highelectrical energy impingement resistance to high electrical energy input182 from a high electrical energy impingement source, such as alightning strike 180. As shown in FIG. 9, when the high electricalenergy impingement source, such as the lightning strike 180, hits themolybdenum composite hybrid laminate 100 of a composite structure 104(see FIG. 4), high electrical energy input 182 occurs. The surfacetreated molybdenum foil layers 122 act as electrical energy dissipationpaths 186 to rapidly conduct away electrical current 184, resulting inimproved lightning strike 180 attenuation or dissipation by themolybdenum composite hybrid laminate 100. The surface treated molybdenumfoil layers 122 have a sufficient molybdenum electrical conductivity 128(see FIG. 4) which is high and a sufficient molybdenum thermalconductivity 130 (see FIG. 4) which is high to enable the surfacetreated molybdenum foil layers 122 to act as the electrical energydissipation paths 186 thereby improving lightning strike 180 attenuationor dissipation of the composite structure 104 (see FIG. 4). The highmolybdenum melting point 132 (see FIG. 4), the high molybdenum thermalconductivity 130 (see FIG. 4), and the high molybdenum electricalconductivity 128 (see FIG. 4) of the surface treated molybdenum foillayers 122 in the molybdenum composite hybrid laminate 100 enable themolybdenum composite hybrid laminate 100 to perform well while beingsubjected to extremely high electrical energy input 182 (see FIG. 9).The high molybdenum stiffness 124 (see FIG. 4) and the high molybdenumstrength 126 (see FIG. 4), along with a low coefficient of thermalexpansion (CTE) of the surface treated molybdenum foil layers 122,further provide improved mechanical properties. Typical CTE values ofmolybdenum are favorably compatible with typical CTE values of compositematerials used in composite lay ups. For example, molybdenum may have atypical CTE value of between about 2.5×10⁻⁶ to about 3.5×10⁻⁶inches/inch/° F. (degrees Fahrenheit), and composite materials used incomposite lay ups may have typical CTE values of between about 0.5×10⁻⁶to about 6.0×10⁻⁶ inches/inch/° F. The surface treated molybdenum foillayers 122 applied to the composite material layers 106, such as, forexample, graphite/resin based material layers 164 (see FIG. 9) providestructural advantages along with improved lightning strike 180attenuation or dissipation.

Each molybdenum composite hybrid laminate 100 for improving lightningstrike 180 attenuation of a composite structure 104 comprises aplurality of composite material layers 106 (see FIG. 9), and eachcomposite material layer 106 comprises a fiber-reinforced polymericmaterial 108 (see FIG. 4). Preferably, the composite material layer 106comprises a graphite/resin based material layer 164. The molybdenumcomposite hybrid laminate 100 further comprises a plurality of surfacetreated molybdenum foil layers 122 (see FIG. 9) interweaved between thecomposite material layers 106. As discussed above, the surface treatedmolybdenum foil layers 122 have a sufficient molybdenum stiffness 124(see FIG. 4) to leverage the fiber tensile strength 116 (see FIG. 4) andthe fiber stiffness 118 (see FIG. 4) of the off-axis fibers 110 (seeFIG. 4) in adjacent composite material layers 106 via Poisson's effectsin the surface treated molybdenum foil layers 122. The surface treatedmolybdenum foil layers 122 are separate from each other and have asufficient molybdenum electrical conductivity 128 (see FIG. 4) to enablethe surface treated molybdenum foil layers 122 to perform as anelectrical bus 160 (see FIG. 15). The molybdenum composite hybridlaminate 100 further comprises a plurality of adhesive layers 134 (seeFIG. 9) disposed between and bonding adjacent layers of the compositematerial layers 106 and the surface treated molybdenum foil layers 122.The adhesive layers 134 (see FIG. 9) may act as electrical insulationlayers 166 (see FIG. 9) for the surface treated molybdenum foil layers122. The molybdenum composite hybrid laminate 100 is preferably used ina composite structure 104 (see FIG. 4), such as an aircraft structure 10(see FIG. 1), and improves lightning strike 180 attenuation ordissipation of the composite structure 104.

In another embodiment of the disclosure, there is provided a method 470of improving lightning strike 180 (see FIG. 9) attenuation of acomposite structure 104 (see FIG. 4) using molybdenum foil layers 122.FIG. 23 is a flow diagram illustrating one of the exemplary embodimentsof the method 470 of improving lightning strike 180 attenuation of thecomposite structure 104 (see FIG. 4), such as aircraft structure 10 (seeFIG. 1). The method 470 comprises step 472 of treating a surface 125 aor 125 b (see FIG. 6) of each of a plurality of molybdenum foil layers122 (see FIG. 9). Treating the surface 125 a or 125 b of the molybdenumfoil layers 122 may comprise one or more surface treatments comprisingsol gel surface treatment, water based sol gel paint, grit blasting,sanding, sandblasting, solvent wiping, abrading, laser ablation,chemical cleaning, chemical etching, or another suitable surfacetreatment.

The method 470 further comprises step 474 of interweaving the surfacetreated molybdenum foil layers 122 with a plurality of compositematerial layers 106 (see FIG. 9). The molybdenum foil layers 122 act aselectrical energy dissipation paths 186 (see FIG. 9) improving lightningstrike 180 attenuation of a composite structure 104. The molybdenum foillayers 122 have a sufficient molybdenum stiffness 124 (see FIG. 4) toleverage a fiber tensile strength 116 (see FIG. 4) and a fiber stiffness118 (see FIG. 4) of off-axis fibers 110 (see FIG. 4) in adjacentcomposite material layers 106 via Poisson's effects in the molybdenumfoil layers 122. The molybdenum foil layers 122 further have asufficient molybdenum electrical conductivity 128 (see FIG. 4) and asufficient molybdenum thermal conductivity 130 (see FIG. 4) to enablethe molybdenum foil layers 122 to act as electrical energy dissipationpaths 186 (see FIG. 9) improving lightning strike 180 (see FIG. 9)attenuation of the composite structure 104 (see FIG. 4).

The method 470 further comprises step 476 of bonding with an adhesivelayer 134 (see FIG. 9) each of the surface treated molybdenum foillayers 122 to adjacent composite material layers 106 (see FIG. 9) toform a molybdenum composite hybrid laminate 100 (see FIG. 9) havingimproved yield strength 102 (see FIG. 4). The interweaving step 474 andbonding step 476 may further comprise one or more of compacting,consolidating, and curing the interweaved surface treated molybdenumfoil layers 122 and the composite material layers 106. The method 470further comprises step 478 of using the molybdenum composite hybridlaminate 100 in the composite structure 104 to improve lightning strike180 attenuation of the composite structure 104.

In another embodiment of the disclosure, there is provided a molybdenumcomposite hybrid laminate 100 to conduct current and act as an aircraftcomposite keel beam 240 (see FIG. 15) in a composite structure 104 (seeFIG. 4), such as in an aircraft 10 (see FIG. 1). An aircraft keel beam26, as shown in FIG. 1, is typically at the lower portion of thefuselage 12 (see FIG. 1) and essentially ties the fuselage 12 together.Lightweight aircraft composite structures, such as keel beams, requireadditional structurally parasitic conductors to effectively dispersecurrent from a lightning strike 180 (see FIG. 15). FIG. 15 is anillustration of a schematic diagram of another one of the embodiments ofa molybdenum composite hybrid laminate 100 of the disclosure where thesurface treated molybdenum foil layers 122 act as both an aircraftcomposite keel beam 240 and current return paths 242 for lightningstrikes 180. As shown in FIG. 15, when the high electrical energyimpingement source, such as a lightning strike 180, hits the molybdenumcomposite hybrid laminate 100 of a composite structure 104 (see FIG. 4),high electrical energy input 182 occurs. The electrical current 184 (seeFIG. 15) may be conducted by the surface treated molybdenum foil layers122 in the molybdenum composite hybrid laminate 100. The surface treatedmolybdenum foil layers 122 enable higher molybdenum strength 126 (seeFIG. 4) and higher molybdenum stiffness 124 (see FIG. 4) of thecomposite structure 104. Also, the high molybdenum electricalconductivity 128 (see FIG. 4) of the surface treated molybdenum foillayers 122 enables the surface treated molybdenum foil layers 122 toperform well as an electrical bus 160 (see FIG. 15). In addition, thesurface treated molybdenum foil layers 122 may act as current returnpaths 242 to rapidly conduct away electrical current 184, resulting inimproved lightning strike 180 protection by the molybdenum compositehybrid laminate 100. The surface treated molybdenum foil layers 122 havea sufficient molybdenum strength 126 (see FIG. 4), a sufficientmolybdenum stiffness 124 (see FIG. 4), and a sufficient molybdenumelectrical conductivity 128 (see FIG. 4) to enable the surfacemolybdenum foil layers 122 to act as an aircraft composite keel beam 240(see FIG. 15) conducting electrical current 184 and providing a currentreturn path 242 (see FIG. 15) for lightning strikes 180 (see FIG. 15) inthe composite structure 104 (see FIG. 4). Due to enhanced mechanicalproperties and the ability to carry electrical current 184, the surfacetreated molybdenum foil layers 122 provide a uniquely advantageousmolybdenum composite hybrid laminate 100 that may act effectively bothas an aircraft composite keel beam 240 in aircraft design and as acurrent return path 242 for lightning strikes 180, which may result inoverall reduced weight and cost. The surface treated molybdenum foillayers 122 provide a lightweight, high performing aircraft compositekeel beam 240 that is effective in conducting electrical current 184 andacting as a lightning strike 180 current return path 242.

As shown in FIG. 15, each molybdenum composite hybrid laminate 100comprises a plurality of composite material layers 106, and eachcomposite material layer 106 comprises a fiber-reinforced polymericmaterial 108 (see FIG. 4). Preferably, the composite material layer 106comprises a graphite/resin based material layer 164 (see FIG. 10). Themolybdenum composite hybrid laminate 100 further comprises a pluralityof surface treated molybdenum foil layers 122 interweaved between thecomposite material layers 106. As discussed above, the surface treatedmolybdenum foil layers 122 have a sufficient molybdenum stiffness 124(see FIG. 4) to leverage the fiber tensile strength 116 (see FIG. 4) andthe fiber stiffness 118 (see FIG. 4) of the off-axis fibers 110 (seeFIG. 4) in adjacent composite material layers 106 via Poisson's effectsin the surface treated molybdenum foil layers 122. The molybdenum foillayers 122 further have a sufficient molybdenum strength 126 (see FIG.4), a sufficient molybdenum stiffness 124 (see FIG. 4), and thesufficient molybdenum electrical conductivity 128 (see FIG. 4) to enablethe molybdenum foil layers 122 to act as an aircraft composite keel beam240 (see FIG. 15) conducting electrical current 184 (see FIG. 15)) andproviding a current return path 242 (see FIG. 15) for lightning strikes180 (see FIG. 15). The molybdenum composite hybrid laminate 100 furthercomprises a plurality of adhesive layers 134 (see FIG. 15) disposedbetween and bonding adjacent layers of the composite material layers 106and the surface treated molybdenum foil layers 122. The adhesive layers134 (see FIG. 15) may act as electrical insulation layers 166 (see FIG.15) for the surface treated molybdenum foil layers 122. The molybdenumcomposite hybrid laminate 100 is preferably used in a compositestructure 104 (see FIG. 4), such as an aircraft structure 10 (seeFIG. 1) and conducts electrical current 184 and provides the currentreturn path 242 for lightning strikes 180 in the aircraft compositestructure 104.

In another embodiment of the disclosure, there is provided a method 450of fabricating into an aircraft structure 10 (see FIG. 1) an aircraftcomposite keel beam 240 (see FIG. 15) for dispersing electrical current184 (see FIG. 15) from a lightning strike 180 (see FIG. 15). The method450 uses molybdenum foil layers 122 (see FIG. 15). FIG. 22 is a flowdiagram illustrating one of the exemplary embodiments of the method 450of fabricating the aircraft composite keel beam 240. The method 450comprises step 452 of treating a surface 125 a or 125 b (see FIG. 6) ofeach of a plurality of molybdenum foil layers 122. Treating the surface125 a or 125 b of the molybdenum foil layers 122 may comprise one ormore surface treatments comprising sol gel surface treatment, waterbased sol gel paint, grit blasting, sanding, sandblasting, solventwiping, abrading, laser ablation, chemical cleaning, chemical etching,or another suitable surface treatment.

The method 450 further comprises step 454 of interweaving the surfacetreated molybdenum foil layers 122 with a plurality of compositematerial layers 106 (see FIG. 15). The molybdenum foil layers 122 act asboth an aircraft composite keel beam 240 (see FIG. 15) and a currentreturn path 242 (see FIG. 15) dispersing electrical current 184 from thelightning strike 180 to a composite structure 104 (see FIG. 4) such asan aircraft structure 10 (see FIG. 1). The molybdenum foil layers 122have a sufficient molybdenum stiffness 124 (see FIG. 4) to leverage afiber tensile strength 116 (see FIG. 4) and a fiber stiffness 118 (seeFIG. 4) of off-axis fibers 110 (see FIG. 4) in adjacent compositematerial layers 106 via Poisson's effects in the molybdenum foil layers122. The molybdenum foil layers 122 further have a sufficient molybdenumstrength 126 (see FIG. 4), a sufficient molybdenum stiffness 124 (seeFIG. 4), and a sufficient molybdenum electrical conductivity 128 (seeFIG. 4) to enable the molybdenum foil layers 122 to act as the aircraftcomposite keel beam 240 (see FIG. 15) and the current return path 242(see FIG. 15) for dispersing electrical current 184 (see FIG. 15) fromthe lightning strike 180 (see FIG. 15) to the aircraft structure 10 (seeFIG. 1).

The method 450 further comprises step 456 of bonding with an adhesivelayer 134 each of the surface treated molybdenum foil layers 122 toadjacent composite material layers 106 to form a molybdenum compositehybrid laminate 100 having improved yield strength 102 (see FIG. 4). Theinterweaving step 454 and bonding step 456 may further comprise one ormore of compacting, consolidating, and curing the interweaved surfacetreated molybdenum foil layers 122 and the composite material layers106. The method 450 further comprises step 458 of using the molybdenumcomposite hybrid laminate 100 in the composite structure 104, such asthe aircraft structure 10 (see FIG. 1), to disperse electrical current184 (see FIG. 15) from the lightning strike 180 to the compositestructure 104, such as the aircraft structure 10.

In another embodiment of the disclosure, there is provided a molybdenumcomposite hybrid laminate 100 (see FIG. 10) to improve thermalimpingement 190 (see FIG. 10) resistance of a composite structure 104(see FIG. 4). FIG. 10 is an illustration of a schematic diagram ofanother one of the embodiments of the molybdenum composite hybridlaminate 100 of the disclosure where the surface treated molybdenum foillayers 122 act as both thermal energy dissipation paths 196 and thermalpenetration barriers 198 improving thermal impingement 190 resistance tohigh thermal energy input 192 from a thermal impingement 190, such as alaser beam or X-ray. In this embodiment, the surface treated molybdenumfoil layers 122 have a sufficient molybdenum thermal conductivity 130(see FIG. 4) which is high that enables the surface treated molybdenumfoil layers 122 to act as thermal energy dissipation paths 196 (see FIG.10) for thermal energy flow 194 to improve thermal impingement 190resistance of the composite structure 104 (see FIG. 4). In addition, thesurface treated molybdenum foil layers 122 have a sufficient molybdenummelting point 132 (see FIG. 4) which is very high that enables thesurface treated molybdenum foil layers 122 to act as thermal penetrationbarriers 198 (see FIG. 10) further improving thermal impingement 190resistance of the composite structure 104. By using the surface treatedmolybdenum foil layers 122 as replacement layers in the compositestructure 104, improved thermal impingement 190 resistance is achieveddue to the very high molybdenum melting point 132 (see FIG. 4) and thehigh molybdenum thermal conductivity 130 (see FIG. 4) of the surfacetreated molybdenum foil layers 122. The surface treated molybdenum foillayers 122 provide significant thermal penetration barriers 198 tothermal impingement 190 or penetration of the composite structure 104due to high molybdenum melting point 132 (see FIG. 4) and the highmolybdenum thermal conductivity 130 (see FIG. 4) which providedissipation of thermal energy input 192 (see FIG. 10) when applied in alocalized area.

As shown in FIG. 10, each molybdenum composite hybrid laminate 100 forimproving thermal impingement 190 resistance comprises a plurality ofcomposite material layers 106 (see FIG. 10), and each composite materiallayer 106 comprises a fiber-reinforced polymeric material 108 (see FIG.4). Preferably, the composite material layer 106 comprises agraphite/resin based material layer 164. The molybdenum composite hybridlaminate 100 further comprises a plurality of surface treated molybdenumfoil layers 122 interweaved between the composite material layers 106.The surface treated molybdenum foil layers 122 have a sufficientmolybdenum stiffness 124 (see FIG. 4) to leverage the fiber tensilestrength 116 (see FIG. 4) and the fiber stiffness 118 (see FIG. 4) ofthe off-axis fibers 110 (see FIG. 4) in adjacent composite materiallayers 106 via Poisson's effects in the surface treated molybdenum foillayers 122. As shown in FIG. 10, the molybdenum composite hybridlaminate 100 further comprises a plurality of adhesive layers 134 (seeFIG. 10) disposed between and bonding adjacent layers of the compositematerial layers 106 and the surface treated molybdenum foil layers 122.The adhesive layers 134 (see FIG. 10) may act as electrical insulationlayers 166 (see FIG. 10) for the surface treated molybdenum foil layers122. The molybdenum composite hybrid laminate 100 is preferably used ina composite structure 104 (see FIG. 4), such as an aircraft structure 10(see FIG. 1) and improves thermal impingement 190 resistance of thecomposite structure 104.

In another embodiment of the disclosure, there is provided a method 490of improving thermal impingement 190 (see FIG. 10) resistance of acomposite structure 104 using molybdenum foil layers 122 (see FIG. 10).FIG. 24 is a flow diagram illustrating one of the exemplary embodimentsof the method 490 of improving thermal impingement 190 (see FIG. 10)resistance of the composite structure 104. The method 490 comprises step492 of treating a surface 125 a or 125 b of each of a plurality ofmolybdenum foil layers 122 (see FIG. 10). Treating the surface 125 a or125 b of the molybdenum foil layers 122 may comprise one or more surfacetreatments comprising sol gel surface treatment, water based sol gelpaint, grit blasting, sanding, sandblasting, solvent wiping, abrading,laser ablation, chemical cleaning, chemical etching, or another suitablesurface treatment.

The method 490 further comprises step 494 of interweaving the surfacetreated molybdenum foil layers 122 with a plurality of compositematerial layers 106 (see FIG. 10). The molybdenum foil layers 122 act asthermal penetration barriers 198 (see FIG. 10) and thermal energydissipation paths 196 (see FIG. 10) improving thermal impingement 190(resistance of a composite structure. The molybdenum foil layers 122have a sufficient molybdenum stiffness 124 (see FIG. 4) to leverage afiber tensile strength 116 (see FIG. 4) and a fiber stiffness 118 (seeFIG. 4) of off-axis fibers 110 (see FIG. 4) in adjacent compositematerial layers 106 via Poisson's effects in the molybdenum foil layers122. The molybdenum foil layers 122 further have a sufficient molybdenummelting point 132 (see FIG. 4) and a sufficient molybdenum thermalconductivity 130 (see FIG. 4) to enable the molybdenum foil layers 122to act as thermal penetration barriers 198 (see FIG. 10) and thermalenergy dissipation paths 196 (see FIG. 10) improving thermal impingement190 (see FIG. 10) resistance of the composite structure 104 (see FIG.4).

The method 490 further comprises step 496 of bonding with an adhesivelayer 134 (see FIG. 10) each of the surface treated molybdenum foillayers 122 to adjacent composite material layers 106 to form amolybdenum composite hybrid laminate 100 (see FIG. 10) having improvedyield strength 102 (see FIG. 4). The interweaving step 494 and bondingstep 496 may further comprise one or more of compacting, consolidating,and curing the interweaved surface treated molybdenum foil layers 122and the composite material layers 106. The method 490 further comprisesstep 498 of using the molybdenum composite hybrid laminate 100 in thecomposite structure 104 to improve thermal impingement 190 resistance ofthe composite structure 104.

In another embodiment of the disclosure, there is provided a molybdenumcomposite hybrid laminate 100 (see FIG. 11) to improve impact 200 (seeFIG. 11) durability of a composite structure 104 (see FIG. 4). FIG. 11is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate 100 of thedisclosure where the surface treated molybdenum foil layers 122 act asload dissipation paths 206 (see FIG. 11) for improved impact 200durability. The surface treated molybdenum foil layers 122 have asufficient molybdenum stiffness 124 which is very high and a sufficientmolybdenum strength 126 which enables the surface treated molybdenumfoil layers 122 to draw load 204 away from a point of impact 202 by animpact 200 source, such as, for example, hail strikes or bird strikes,thereby blunting the concentrated impact force. The surface treatedmolybdenum foil layers 122 spread the load 204 over a larger area alongthe surface treated molybdenum foil layers 122 improving impactdurability and impact resistance of the composite structure 104. Thecomposite material layers 106 (see FIG. 11) are spared the transfer ofload 204 deep into the molybdenum composite hybrid laminate 100, therebyreducing detrimental effects associated with the point of impact 202.The use of the high stiffness and high strength surface treatedmolybdenum foil layers 122 enables much thinner gauges while also addingsuch benefits as improved lightning resistance and improved structuralperformance.

As shown in FIG. 11, each molybdenum composite hybrid laminate 100 forimproving impact 200 durability comprises a plurality of compositematerial layers 106, and each composite material layer 106 comprises afiber-reinforced polymeric material 108 (see FIG. 4). Preferably, thecomposite material layer 106 comprises a graphite/resin based materiallayer 164. The molybdenum composite hybrid laminate 100 furthercomprises a plurality of surface treated molybdenum foil layers 122 (seeFIG. 11) interweaved between the composite material layers 106. Thesurface treated molybdenum foil layers 122 have a sufficient molybdenumstiffness 124 (see FIG. 4) to leverage the fiber tensile strength 116(see FIG. 4) and the fiber stiffness 118 (see FIG. 4) of the off-axisfibers 110 (see FIG. 4) in adjacent composite material layers 106 viaPoisson's effects in the surface treated molybdenum foil layers 122. Thesurface treated molybdenum foil layers 122 further have a sufficientmolybdenum stiffness 124 (see FIG. 4) and a sufficient molybdenumstrength 126 (see FIG. 4) to enable the surface treated molybdenum foillayers 122 to draw load 204 (see FIG. 11) away from the point of impact202 (see FIG. 11) improving impact 200 durability. The molybdenumcomposite hybrid laminate 100 further comprises a plurality of adhesivelayers 134 (see FIG. 11) disposed between and bonding adjacent layers ofthe composite material layers 106 and the surface treated molybdenumfoil layers 122. The adhesive layers 134 (see FIG. 11) may act asinsulation layers 166 (see FIG. 11) for the surface treated molybdenumfoil layers 122. The molybdenum composite hybrid laminate 100 ispreferably used in a composite structure 104 (see FIG. 4), such as anaircraft structure 10 (see FIG. 1), and improves impact durability ofthe composite structure 104.

In another embodiment there is provided a method 530 of improving impact200 (see FIG. 11) durability of a composite structure 104 (see FIG. 4)using molybdenum foil layers 122. FIG. 26 is a flow diagram illustratingone of the exemplary embodiments of the method 530 of improving impactdurability. The method 530 comprises step 532 of treating a surface 125a or 125 b (see FIG. 6) of each of a plurality of molybdenum foil layers122 (see FIG. 11). Treating the surface 125 a or 125 b of the molybdenumfoil layers 122 may comprise one or more surface treatments comprisingsol gel surface treatment, water based sol gel paint, grit blasting,sanding, sandblasting, solvent wiping, abrading, laser ablation,chemical cleaning, chemical etching, or another suitable surfacetreatment.

The method 530 further comprises step 534 of interweaving the surfacetreated molybdenum foil layers 122 with a plurality of compositematerial layers 106 (see FIG. 11). The molybdenum foil layers 122 act asload dissipation paths 206 (see FIG. 11) improving impact durability ata point of impact 202 from an impact 200 source, such as hail strikes,bird strikes, or another impact source. The molybdenum foil layers 122preferably improve resistance to impact 200 damage such as from hailstrikes and bird strikes. The molybdenum foil layers 122 have asufficient molybdenum stiffness 124 (see FIG. 4) to leverage a fibertensile strength 116 (see FIG. 4) and a fiber stiffness 118 (see FIG. 4)of off-axis fibers 110 (see FIG. 4) in adjacent composite materiallayers 106 via Poisson's effects in the molybdenum foil layers 122. Themolybdenum foil layers 122 further have a sufficient molybdenumstiffness 124 (see FIG. 4) and a sufficient molybdenum strength 126 (seeFIG. 4) to enable the molybdenum foil layers 122 to act as loaddissipation paths 206 (see FIG. 11) improving impact durability of thecomposite structure 104.

The method 530 further comprises step 536 of bonding with an adhesivelayer 134 (see FIG. 11) each of the surface treated molybdenum foillayers 122 to adjacent composite material layers 106 to form amolybdenum composite hybrid laminate 100 (see FIG. 11) having improvedyield strength 102 (see FIG. 4). The interweaving step 534 and bondingstep 536 may further comprise one or more of compacting, consolidating,and curing the interweaved surface treated molybdenum foil layers 122and the composite material layers 106. The method 530 further comprisesstep 538 of using the molybdenum composite hybrid laminate 100 in thecomposite structure 104 to improve impact durability of the compositestructure 104. The composite structure 104 preferably comprises anaircraft structure 10 (see FIG. 10).

In another embodiment of the disclosure, there is provided a molybdenumcomposite hybrid laminate 100 to steer load 214 (see FIG. 12A) via mainload paths 212 a and secondary load paths 212 b (see FIG. 12A) in acomposite structure 104 (see FIG. 12A). FIG. 12A is an illustration of aschematic diagram of another one of the embodiments of a molybdenumcomposite hybrid laminate 100 of the disclosure showing the surfacetreated molybdenum foil layers 122 and composite material layer 106 ofthe composite structure 104 steering load 214 around a non-load bearingarea 210, such as, for example, access holes, access panels, systemspenetrations, and other design artifacts. FIG. 12A shows the non-loadbearing area 210 with a system penetration element 211. FIG. 12B is anillustration of a schematic diagram of a cross-section taken at lines12B-12B of FIG. 12A. FIG. 12B shows the non-load bearing area 210 withthe system penetration element 211, the composite material layer 106 ofthe composite structure 104, and the surface treated molybdenum foillayers 122 acting as load steering paths 215. When non-load bearingareas 210, such as access holes, systems penetrations, or other suitabledesign artifacts, are needed in composite structures, it is necessary topad-up the lay up of the composite structure 104 to facilitate the flowof load 214 around these non-load bearing areas 210. The surface treatedmolybdenum foil layers 122 have a sufficient molybdenum stiffness 124(see FIG. 4) which is high and a sufficient molybdenum strength 126 (seeFIG. 4) which is high to enable the surface treated molybdenum foillayers 122 to steer load 214 in load steering paths 215 (see FIG. 12B)around the non-load bearing area 210 in the composite structure 104. Thesurface treated molybdenum foil layers 122 have a very high molybdenumstiffness 124 (see FIG. 4) and a very high molybdenum strength 126 (seeFIG. 4) and will draw load 214 and reinforce the non-load bearing areas210, such as, access holes, systems penetrations, and other designartifacts, without needing to add additional thickness to the compositestructure 104. The surface treated molybdenum foil layers 122 enable theload 214 to travel in efficient, thin, customized load steering paths215. The efficiency may provide optimal advantages with respect to cost,part volume, and weight of the composite structure 104.

Each molybdenum composite hybrid laminate 100 for steering load 214around the non-load bearing areas 210 in the composite structure 104comprises a plurality of composite material layers 106, and eachcomposite material layer 106 comprises a fiber-reinforced polymericmaterial 108 (see FIG. 4). Preferably, the composite material layer 106comprises a graphite/resin based material layer. The molybdenumcomposite hybrid laminate 100 further comprises a plurality of surfacetreated molybdenum foil layers 122 interweaved between the compositematerial layers 106. The surface treated molybdenum foil layers 122 havea sufficient molybdenum stiffness 124 (see FIG. 4) to leverage the fibertensile strength 116 (see FIG. 4) and the fiber stiffness 118 (see FIG.4) of the off-axis fibers 110 (see FIG. 4) in adjacent compositematerial layers 106 via Poisson's effects in the surface treatedmolybdenum foil layers 122. The surface treated molybdenum foil layers122 further have a sufficient molybdenum stiffness 124 (see FIG. 4) anda sufficient molybdenum strength 126 (see FIG. 4) to enable the surfacetreated molybdenum foil layers 122 to steer load 214 in load steeringpaths 215 around non-load bearing areas 210 (see FIG. 12A). Themolybdenum composite hybrid laminate 100 further comprises a pluralityof adhesive layers 134 disposed between and bonding adjacent layers ofthe composite material layers 106 and the surface treated molybdenumfoil layers 122. The molybdenum composite hybrid laminate 100 ispreferably used in a composite structure 104 (see FIG. 4), such as anaircraft structure 10 (see FIG. 1), and steers load 214 around non-loadbearing areas 210 in the composite structure 104.

In another embodiment of the disclosure, there is provided a method 550of steering load 214 (see FIG. 12A) around non-load bearing areas 210(see FIG. 12A) in a composite structure 104 (see FIG. 4) usingmolybdenum foil layers 122. FIG. 27 is a flow diagram illustrating oneof the exemplary embodiments of the method 550 of steering load 214around non-load bearing areas 210. The non-load bearing areas 210 maycomprise access holes, access panels, systems penetrations, or othersuitable design artifacts. The method 550 comprises step 552 of treatinga surface 125 a or 125 b (see FIG. 6) of each of a plurality ofmolybdenum foil layers 122 (see FIG. 12A). Treating the surface 125 a or125 b of the molybdenum foil layers 122 may comprise one or more surfacetreatments comprising sol gel surface treatment, water based sol gelpaint, grit blasting, sanding, sandblasting, solvent wiping, abrading,laser ablation, chemical cleaning, chemical etching, or another suitablesurface treatment.

The method 550 further comprises step 554 of interweaving the surfacetreated molybdenum foil layers 122 (see FIG. 12A) with a plurality ofcomposite material layers 106. The molybdenum foil layers 122 act asload steering paths 215 (see FIGS. 12A-B) steering load 214 aroundnon-load bearing areas 210 in the composite structure 104. Themolybdenum foil layers 122 have a sufficient molybdenum stiffness 124(see FIG. 4) to leverage a fiber tensile strength 116 (see FIG. 4) and afiber stiffness 118 (see FIG. 4) of off-axis fibers 110 (see FIG. 4) inadjacent composite material layers 106 via Poisson's effects in themolybdenum foil layers 122. The molybdenum foil layers 122 further havea sufficient molybdenum stiffness 124 (see FIG. 4) and a sufficientmolybdenum strength 126 (see FIG. 4) to enable the molybdenum foillayers 122 to act as load steering paths 215 steering load 214 aroundnon-load bearing areas 210 in the composite structure 104.

The method 550 further comprises step 556 of bonding with an adhesivelayer 134 (see FIG. 4) each of the surface treated molybdenum foillayers 122 to adjacent composite material layers 106 to form amolybdenum composite hybrid laminate 100 (see FIG. 12A) having improvedyield strength 102 (see FIG. 4). The interweaving step 554 and bondingstep 556 may further comprise one or more of compacting, consolidating,and curing the interweaved surface treated molybdenum foil layers 122and the composite material layers 106. The method 550 further comprisesstep 558 of using the molybdenum composite hybrid laminate 100 in thecomposite structure 104 to steer load 214 around the non-load bearingareas 210 in the composite structure 104.

In another embodiment of the disclosure, there is provided a molybdenumcomposite hybrid laminate 100 to improve a cure cycle, such as toimprove cure cycle characteristics, of a composite structure 104 (seeFIG. 13). FIG. 13 is an illustration of a schematic diagram of anotherone of the embodiments of a molybdenum composite hybrid laminate 100 ofthe disclosure where the surface treated molybdenum foil layers 122 actas thermal and temperature controllers 226 for improved cure cycle, suchas improved cure cycle characteristics. Thermal and temperatureuniformity and the ability to control excessive thermal energy due tocure kinetics of the resins can be important fabrication issues whencuring thermosetting composites. FIG. 13 shows excess thermal energy 222being generated in a cure area 220 as the cure in the cure area 220advances at a more rapid rate. The excess thermal energy 222 isconducted away rapidly along thermal energy flow paths 224, therebyreducing the risk of thermal over shooting. The surface treatedmolybdenum foil layers 122 have a sufficient molybdenum thermalconductivity 130 (see FIG. 4) which is high to enable the surfacetreated molybdenum foil layers 122 to act as thermal and temperaturecontrollers 226 improving the cure cycle, such as improving cure cyclecharacteristics, of the composite structure 104 (see FIG. 4). Cure cyclecharacteristics may comprise a cure cycle length, a cure cycle thermalleveling, a cure cycle temperature leveling, a cure cycle thermalcontrol, a cure cycle temperature control, or another suitable curecycle characteristic.

The high molybdenum thermal conductivity 130 (see FIG. 4) enables thesurface treated molybdenum foil layers 122 to perform well structurallywhile assisting in controlling or leveling out the thermal uniformityand temperature for improved cure cycle, such as improved cure cyclecharacteristics. The surface treated molybdenum foil layers 122 mayimprove the overall cure cycle length and thermal robustness due to itsexcellent molybdenum thermal conductivity 130 (see FIG. 4), thus,reducing overall costs of fabrication. The excellent molybdenum thermalconductivity 130 (see FIG. 4) provides improved thermal and temperaturecontrol or leveling in the composite structure 104 (see FIG. 4) andenables more robust fabrication processing cycles. The curing andstructurally advantageous characteristics of the surface treatedmolybdenum foil layers 122 (see FIG. 13) may be tailored to provide anoptimum solution.

As shown in FIG. 13, each molybdenum composite hybrid laminate 100comprises a plurality of composite material layers 106, and eachcomposite material layer 106 comprises a fiber-reinforced polymericmaterial 108 (see FIG. 4). Preferably, the composite material layer 106comprises a graphite/resin based material layer. As shown in FIG. 13,the molybdenum composite hybrid laminate 100 further comprises aplurality of surface treated molybdenum foil layers 122 interweavedbetween the composite material layers 106. The surface treatedmolybdenum foil layers 122 have a sufficient molybdenum stiffness 124(see FIG. 4) to leverage the fiber tensile strength 116 (see FIG. 4) andthe fiber stiffness 118 (see FIG. 4) of the off-axis fibers 110 (seeFIG. 4) in adjacent composite material layers 106 via Poisson's effectsin the surface treated molybdenum foil layers 122. The surface treatedmolybdenum foil layers 122 further have a sufficient molybdenumstiffness 124 (see FIG. 4) and a sufficient molybdenum strength 126 (seeFIG. 4) to enable the surface treated molybdenum foil layers 122 to actas thermal and temperature controllers 226 improving a cure cycle, suchas improving cure cycle characteristics, of the composite structure 104.The molybdenum composite hybrid laminate 100 further comprises aplurality of adhesive layers 134 (see FIG. 13) disposed between andbonding adjacent layers of the composite material layers 106 and thesurface treated molybdenum foil layers 122. The adhesive layers 134 (seeFIG. 13) may act as insulation layers 166 (see FIG. 13) for the surfacetreated molybdenum foil layers 122. The molybdenum composite hybridlaminate 100 is preferably used in a composite structure 104 (see FIG.4), such as an aircraft structure 10 (see FIG. 1).

In another embodiment of the disclosure, there is provided a method 510of improving a cure cycle of a composite structure 104 (see FIG. 4)using molybdenum foil layers 122 (see FIG. 13). FIG. 25 is a flowdiagram illustrating one of the exemplary embodiments of the method 510of improving the cure cycle. The method 510 comprises step 512 oftreating a surface 125 a or 125 b (see FIG. 6) of each of a plurality ofmolybdenum foil layers 122. Treating the surface 125 a or 125 b of themolybdenum foil layers 122 may comprise one or more surface treatmentscomprising sol gel surface treatment, water based sol gel paint, gritblasting, sanding, sandblasting, solvent wiping, abrading, laserablation, chemical cleaning, chemical etching, or another suitablesurface treatment.

The method 510 further comprises step 514 of interweaving the surfacetreated molybdenum foil layers 122 with a plurality of compositematerial layers 106 (see FIG. 13). The molybdenum foil layers 122 act asthermal and temperature controllers 224 (see FIG. 13) improving the curecycle of a composite structure 104 (see FIG. 4). The molybdenum foillayers 122 have a sufficient molybdenum stiffness 124 (see FIG. 4) toleverage a fiber tensile strength 116 (see FIG. 4) and a fiber stiffness118 (see FIG. 4) of off-axis fibers 110 (see FIG. 4) in adjacentcomposite material layers 122 via Poisson's effects in the molybdenumfoil layers 122. The molybdenum foil layers 122 further have asufficient molybdenum thermal conductivity 130 (see FIG. 4) to enablethe molybdenum foil layers 122 to act as thermal and temperaturecontrollers 226 (see FIG. 13) improving the cure cycle of the compositestructure 104 (see FIG. 4). The molybdenum foil layers 122 act asthermal and temperature controllers 226 to improve the cure cycle, suchas improving cure cycle characteristics comprising a cure cycle length,a cure cycle thermal leveling, a cure cycle temperature leveling, a curecycle thermal control, a cure cycle temperature control, or anothersuitable cure cycle characteristic.

The method 510 further comprises step 516 of bonding with an adhesivelayer 134 (see FIG. 13) each of the surface treated molybdenum foillayers 122 to adjacent composite material layers 106 to form amolybdenum composite hybrid laminate 100 (see FIG. 13) having improvedyield strength 102 (see FIG. 4). The interweaving step 514 and bondingstep 516 may further comprise one or more of compacting, consolidating,and curing the interweaved surface treated molybdenum foil layers 122and the composite material layers 106. The method 510 further comprisesstep 518 of using the molybdenum composite hybrid laminate 100 in thecomposite structure 104 to improve the cure cycle of the compositestructure 104.

In other embodiments of the disclosure, there are provided molybdenumcomposite hybrid laminates 100 to draw load 234 (see FIGS. 14A, 14C))via main load paths 232 a and secondary load paths 232 b (see FIGS. 14A,14C) in a composite structure 104 (see FIGS. 14A, 14C) and to reinforcerepair areas 230 (see FIGS. 14A, 14C), such as, for example, holes,weakened areas, damaged areas, and other areas requiring repair, in acomposite structure 104. FIG. 14A is an illustration of a schematicdiagram of another one of the embodiments of a molybdenum compositehybrid laminate 100 of the disclosure showing the surface treatedmolybdenum foil layers 122 of the composite structure 104 reinforcing apatch repair area 230 a, For purposes of this application, a patchrepair means a type of bonded repair in which replacement material isinserted to fill a damaged area. FIG. 14B is an illustration of aschematic diagram of a cross-section taken at lines 14B-14B of FIG. 14A.FIG. 14C is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate 100 of thedisclosure showing the surface treated molybdenum foil layers 122 of thecomposite part 104 reinforcing a scarf repair area 230 b. For purposesof this application, a scarf repair means a type of bonded repair inwhich a damaged area is sanded to produce a tapering effect and thenreplacement material is laid over the damaged area. FIG. 14D is anillustration of a schematic diagram of a cross-section taken at lines14D-14D of FIG. 14C.

FIGS. 14A-14B show the surface treated molybdenum foil layers 122 actingas load drawing paths 235 to draw load 234 (see FIG. 14A) away from therepair area 230, for example, the patch repair area 230 a and provide areinforcement element 236 of the repair area 230, for example, the patchrepair area 230 a. FIGS. 14C-14D show the surface treated molybdenumfoil layers 122 acting as load drawing paths 235 to draw load 234 (seeFIG. 14C) away from the repair area 230, for example, the scarf repairarea 230 b and provide a reinforcement element 236 of the repair area230, for example, the scarf repair area 230 b. By using the surfacetreated molybdenum foil layers 122 as part of the composite structure104, the surface treated molybdenum foil layers 122 enable the load 234to travel in efficient, thin, customized load drawing paths 235 (seeFIGS. 14B, 14D). The high molybdenum strength 126 (see FIG. 4) and highmolybdenum stiffness 124 (see FIG. 4) of the surface treated molybdenumfoil layers 122 enable thinner, customized load drawing paths 235 formore efficient and thinner repairs, without needing to add significantadditional thickness to the composite structure 104. In addition, thesurface treated molybdenum foil layers 122 acting as load drawing paths235 to draw load 234 and provide reinforcement elements 236 to repairareas 230, such as patch repair areas (230 a) and scarf repair areas(230 b), provide for more effective and efficient repairs of compositestructures 104, less aerodynamic drag of vehicles with such compositestructures 104, and improved appearance of the composite structures 104.

Each molybdenum composite hybrid laminate 100 for reinforcing anddrawing load 234 (FIGS. 14A, 14C) away from a repair area 230 (FIGS.14A-14D) comprises a plurality of composite material layers 106. Eachcomposite material layer 106 comprises a fiber-reinforced polymericmaterial 108 (see FIG. 4). Preferably, the composite material layer 106comprises a graphite/resin based material layer. The molybdenumcomposite hybrid laminate 100 further comprises a plurality of surfacetreated molybdenum foil layers 122 interweaved between the compositematerial layers 106. As discussed above, the surface treated molybdenumfoil layers 122 have a sufficient molybdenum stiffness 124 (see FIG. 4)to leverage the fiber tensile strength 116 (see FIG. 4) and the fiberstiffness 118 (see FIG. 4) of the off-axis fibers 110 (see FIG. 4) inadjacent composite material layers 106 via Poisson's effects in thesurface treated molybdenum foil layers 122. The surface treatedmolybdenum foil layers 122 have a sufficient molybdenum stiffness 124(see FIG. 4) and a sufficient molybdenum strength 126 (see FIG. 4) toenable the surface treated molybdenum foil layers 122 to act as loaddrawings paths 235 (see FIGS. 14B, 14D) to draw load 234 away from arepair area 230 and provide reinforcement elements 236 to the repairareas 230 in the composite structure 104. The molybdenum compositehybrid laminate 100 further comprises a plurality of adhesive layers 134disposed between and bonding adjacent layers of the composite materiallayers 106 and the surface treated molybdenum foil layers 122. Themolybdenum composite hybrid laminate 100 is preferably used in acomposite structure 104 (see FIGS. 14A, 14C), such as an aircraftstructure (see FIG. 1), and reinforces repair areas in the compositestructure 104.

In another embodiment of the disclosure, there is provided a method 570of reinforcing and drawing load 234 (FIGS. 14A, 14C) away from a repairarea 230 (FIGS. 14A-14D) in a composite structure 104 using molybdenumfoil layers 122 (FIGS. 14A-14D). FIG. 28 is a flow diagram illustratingone of the exemplary embodiments of the method 570 of reinforcing anddrawing load 234 (FIGS. 14A, 14C) away from the repair area 230 (FIGS.14A-14D). The repair area 230 may comprise a patch repair area 230 a(see FIGS. 14A-14B), a scarf repair area 230 b (see FIGS. 14C-14D),holes, weakened areas, damaged areas or another repair area.

The method 570 comprises step 572 of treating a surface 125 a or 125 b(see FIG. 6) of each of a plurality of molybdenum foil layers 122.Treating the surface 125 a or 125 b of the molybdenum foil layers 122may comprise one or more surface treatments comprising sol gel surfacetreatment, water based sol gel paint, grit blasting, sanding,sandblasting, solvent wiping, abrading, laser ablation, chemicalcleaning, chemical etching, or another suitable surface treatment.

The method 570 further comprises step 574 of interweaving the surfacetreated molybdenum foil layers 122 with a plurality of compositematerial layers 106. The molybdenum foil layers 122 act as reinforcementelements 236 (FIGS. 14A-14D) and load drawing paths 235 (FIGS. 14A-14D)reinforcing and drawing load 234 (FIGS. 14A, 14C) away from a repairarea 230 (FIGS. 14A-14D) in a composite structure 104. The molybdenumfoil layers 122 have a sufficient molybdenum stiffness 124 (see FIG. 4)to leverage a fiber tensile strength 116 (see FIG. 4) and a fiberstiffness 118 (see FIG. 4) of off-axis fibers 110 (see FIG. 4) inadjacent composite material layers 106 via Poisson's effects in themolybdenum foil layers 122. The molybdenum foil layers 122 further havea sufficient molybdenum stiffness 124 (see FIG. 4) and a sufficientmolybdenum strength 126 (see FIG. 4) to enable the molybdenum foillayers 122 to reinforce and draw load 234 away from the repair area 230in the composite structure 104.

The method 570 further comprises step 576 of bonding with an adhesivelayer 134 (see FIG. 4) each of the surface treated molybdenum foillayers 122 to adjacent composite material layers 106 to form amolybdenum composite hybrid laminate 100 (see FIGS. 14A-14D) havingimproved yield strength 102 (see FIG. 4). The interweaving step 574 andbonding step 576 may further comprise one or more of compacting,consolidating, and curing the interweaved surface treated molybdenumfoil layers 122 and the composite material layers 106. The method 570further comprises step 578 of using the molybdenum composite hybridlaminate 10 in the composite structure 104 to reinforce and draw load534 away from the repair area 230 in the composite structure 104.

In another embodiment of the disclosure, there is provided a molybdenumcomposite hybrid laminate 100 (see FIG. 18) to mitigate or eliminateareas of fiber distortion 268 (see FIG. 17) in a composite structure 104using molybdenum foil layers 122 (see FIG. 18). FIG. 17 is anillustration of a schematic diagram of a composite structure 104 havingareas of fiber distortion 268. FIG. 17 shows a pre-cured or curedcomposite structure 260 having fibers 262 and having a T-shapedconfiguration and a non-uniform cross section. FIG. 17 further shows thepre-cured or cured composite structure 260 joined to a compositestructure 104, such as an uncured composite structure 264 having fibers266 and having a uniform cross section. Where the pre-cured or curedcomposite structure 260 is joined to the uncured composite structure264, differences in pressure between the pre-cured or cured compositestructure 260 and the uncured composite structure 264 may producewrinkling of composite material layers 106 and bow waves of fibers 266which may result in areas of fiber distortion 268 (see FIG. 17).

FIG. 18 is an illustration of a schematic diagram of another one of theembodiments of a molybdenum composite hybrid laminate 100 of thedisclosure where the molybdenum foil layers 122 act as fiber stabilizers270 to mitigate or eliminate the areas of fiber distortion 268 (see FIG.17). FIG. 18 shows the pre-cured or cured composite structure 260 havingfibers 262, and having a T-shaped configuration and a non-uniform crosssection. FIG. 18 further shows the pre-cured or cured compositestructure 260 joined to a composite structure 104, such as an uncuredcomposite structure 264 having fibers 266 and having a uniform crosssection. In this embodiment, the surface treated molybdenum foil layers122 (see FIG. 18) may be added to the uncured composite structure 264where the pre-cured or cured composite structure 260 is joined to theuncured composite structure 264. The surface treated molybdenum foillayers 122 have a sufficient molybdenum stiffness 124 (see FIG. 4) and asufficient molybdenum strength 126 (see FIG. 4) to enable the surfacetreated molybdenum foil layers 122 (see FIG. 18) to act as fiberstabilizers 270 (see FIG. 18) mitigating or eliminating fiber distortion268 (see FIG. 17) in the composite structure 104 (see FIG. 18), such asthe uncured composite structure 264, and resulting in stabilized fibers272 (see FIG. 18) in the composite structure 104. In particular, theadditional molybdenum stiffness 124 mitigates or eliminates the bowwaves of fibers 266 (see FIG. 17), which in turn, mitigates oreliminates areas of fiber distortion 268 (see FIG. 17). Further, thesurface treated molybdenum foil layers 122 have a sufficient molybdenumstiffness 124 (see FIG. 4) to leverage a fiber tensile strength 116 (seeFIG. 4) and a fiber stiffness 118 (see FIG. 4) of off-axis fibers 110(see FIG. 4) in adjacent composite material layers 106 (see FIG. 18) viaPoisson's effects in the surface treated molybdenum foil layers 122.

Each molybdenum composite hybrid laminate 100 (see FIG. 18) comprises aplurality of composite material layers 106 (see FIG. 18), and eachcomposite material layer 106 comprises a fiber-reinforced polymericmaterial 108 (see FIG. 4). Preferably, the composite material layer 106comprises a graphite/resin based material layer. The molybdenumcomposite hybrid laminate 100 further comprises one or more surfacetreated molybdenum foil layers 122 interweaved between the compositematerial layers 106. The molybdenum composite hybrid laminate 100further comprises one or more adhesive layers 134 (see FIG. 18) disposedbetween and bonding adjacent layers of the composite material layers 106and the surface treated molybdenum foil layers 122. The molybdenumcomposite hybrid laminate 100 may be used in a composite structure 104and mitigates or eliminates areas of fiber distortion 268 in thecomposite structure 104.

In another embodiment there is provided a method 600 of mitigating fiberdistortion in a composite structure 104 using molybdenum foil layers122. FIG. 29 is a flow diagram illustrating one of the exemplaryembodiments of the method 600 for mitigating fiber distortion. Themethod 600 comprises step 602 of treating a surface 125 a or 125 b (seeFIG. 6) of each of a plurality of molybdenum foil layers 122. Treatingthe surface 125 a or 125 b of the molybdenum foil layers 122 maycomprise one or more surface treatments comprising sol gel surfacetreatment, water based sol gel paint, grit blasting, sanding,sandblasting, solvent wiping, abrading, laser ablation, chemicalcleaning, chemical etching, or another suitable surface treatment.

The method 600 further comprises step 604 of interweaving the surfacetreated molybdenum foil layers 122 with a plurality of compositematerial layers 106. The molybdenum foil layers 122 act as fiberstabilizers 270 (see FIG. 18) mitigating fiber distortion 268 (see FIG.17) in a composite structure 104. The molybdenum foil layers 122 have asufficient molybdenum stiffness 124 to leverage a fiber tensile strength116 and a fiber stiffness 118 of off-axis fibers 110 in adjacentcomposite material layers 106 via Poisson's effects in the molybdenumfoil layers 122. The molybdenum foil layers 122 further have asufficient molybdenum stiffness 124 and a sufficient molybdenum strength126 to enable the molybdenum foil layers 122 to act as fiber stabilizers270 mitigating fiber distortion 268 in the composite structure 104.

The method 600 further comprises step 606 of bonding with an adhesivelayer 134 each of the surface treated molybdenum foil layers 122 toadjacent composite material layers 106 to form a molybdenum compositehybrid laminate 100 (see FIG. 18) having improved yield strength 102(see FIG. 4). The interweaving step 604 and the bonding step 606 mayfurther comprise one or more of compacting, consolidating, and curingthe interweaved surface treated molybdenum foil layers 122 and thecomposite material layers 106. The method 600 further comprises step 608of using the molybdenum composite hybrid laminate 100 in the compositestructure 104 to mitigate fiber distortion 268 in the compositestructure 104.

FIG. 19 is a flow diagram illustrating one of the exemplary embodimentsof a method 300 of forming a molybdenum composite hybrid laminate 100(see FIG. 4) or a molybdenum laminate lay up 101 or 150 (see FIGS. 5-6).The method 300 comprises step 302 of treating a surface 125 a or 125 b(see FIG. 6) of each of a plurality of molybdenum foil layers 122 or ofeach of a plurality of molybdenum foils 123 (see FIG. 6). The molybdenumfoil layer 122 or molybdenum foil 123 is preferably surface treated toimprove bonding between the molybdenum foil layer 122 or molybdenum foil123 and an adjacent composite material layer 106 (see FIG. 4). Thesurface 125 a or 125 b of the molybdenum foil layer 122 or molybdenumfoil 123 may be treated with a surface treatment process comprising solgel surface treatment, water based sol gel paint, grit blasting,sanding, sandblasting, solvent wiping, abrading, laser ablation,chemical cleaning, chemical etching, or another suitable surfacetreatment process.

The method 300 further comprises step 304 of interweaving the surfacetreated molybdenum foil layers 122 with a plurality of compositematerial layers 106. Preferably, each composite material layer 106comprises a fiber-reinforced polymeric material 108 (see FIGS. 4, 5).Preferably, the composite material layer 106 comprises a graphite/resinbased material layer. The surface treated molybdenum foil layers 122leverage the fiber tensile strength 116 (see FIG. 4) and the fiberstiffness 118 (see FIG. 4) of the off-axis fibers 110 (see FIG. 4) inadjacent composite material layers 106 via Poisson's effects in thesurface treated molybdenum foil layers 122. In an embodiment with themolybdenum laminate layup 101 (see FIG. 5), two or more of the compositematerial layers 106 may each have a cutout portion 144 (see FIG. 5)comprising surface treated molybdenum foil 123, and for this embodiment,the method 300 may further comprise staggering interior edges 148 (seeFIG. 5) of the cutout portions 144 to prevent an overlay of two or moreinterior edges 148 in order to provide improved load distribution by themolybdenum foil 123.

The method 300 further comprises step 306 of bonding with an adhesivelayer 134 (see FIG. 4) each of the surface treated molybdenum foillayers 122 to adjacent composite material layers 106 to form themolybdenum composite hybrid laminate 100 having improved yield strength102 (see FIG. 4). In an embodiment with the molybdenum laminate layup101 (see FIG. 5), the method 300 may further comprise bonding with anadhesive layer 134 each of the surface treated molybdenum foils 123 ofthe molybdenum foil containing layers 146 to adjacent composite materiallayers 106 to form the molybdenum laminate layup 101. The interweavingstep 304 and/or bonding step 306 of the method 300 may further compriseone or more of compacting, consolidating, and curing the interweavedsurface treated molybdenum foil layers 122 or molybdenum foils 123 andthe composite material layers 106. For example, the consolidating andcuring may be carried out via autoclave processing, vacuum bagprocessing, or another known process. Autoclave processing involves useof an autoclave pressure vessel which provides curing conditions for acomposite material, and the application of vacuum, pressure, heat uprate, and cure temperature may be controlled.

The method 300 further comprises step 308 of using the molybdenumcomposite hybrid laminate 100 or the molybdenum laminate layup 101 or150 in a composite structure 104 (see FIG. 4), such as an aircraftstructure 10 (see FIG. 1).

In another embodiment, the method 300 may further comprise after usingthe molybdenum composite hybrid laminate 100 in a composite structure104, coupling the molybdenum composite hybrid laminate 100 to one ormore electrical sensor devices 168 (see FIG. 16) in order to driveelectrical current 170 (see FIG. 16) through the molybdenum foil layers122, monitoring any changes in flow of the electrical current 170through the molybdenum foil layers 122, and obtaining structural healthdata 254 (see FIG. 16) of the composite structure 104.

As discussed in detail above, in one embodiment, the surface treatedmolybdenum foil layers 122 used in the method 300 may have a sufficientmolybdenum electrical conductivity 128 (see FIG. 4) to enable thesurface treated molybdenum foil layers 122 to act as an electrical bus160 (see FIG. 16) in an aircraft structure 10, resulting in an overallreduced weight of the aircraft structure 10 (see FIG. 1). As discussedin detail above, in another embodiment, the surface treated molybdenumfoil layers 122 used in the method 300 may have a sufficient molybdenumstrength 126 (see FIG. 4), a sufficient molybdenum stiffness 124 (seeFIG. 4), and a sufficient molybdenum electrical conductivity 128 (seeFIG. 4) to enable the molybdenum foil layers 122 to act as an aircraftkeel beam 240 (see FIG. 15) and current return path 242 dispersingelectrical current 184 (see FIG. 15) from a lightning strike 180 (seeFIG. 15) to a composite structure 104 (see FIG. 4), such as an aircraftstructure 10 (see FIG. 1).

As discussed in detail above, in another embodiment, the surface treatedmolybdenum foil layers 122 used in the method 300 may have a sufficientmolybdenum electrical conductivity 128 (see FIG. 4) and a sufficientmolybdenum thermal conductivity 130 (see FIG. 4) to enable themolybdenum foil layers 122 to act as electrical energy dissipation paths186 (see FIG. 9) improving lightning strike 180 (see FIG. 9) attenuationof a composite structure 104 (see FIG. 4). As discussed in detail above,in another embodiment, the surface treated molybdenum foil layers 122used in the method 300 may have a sufficient molybdenum melting point132 (see FIG. 4) and a sufficient molybdenum thermal conductivity 130(see FIG. 4) that enable the molybdenum foil layers 122 to act asthermal penetration barriers 198 and thermal energy dissipation paths196 (see FIG. 10) improving thermal impingement resistance of thecomposite structure 104 (see FIG. 4).

As discussed in detail above, in another embodiment, the surface treatedmolybdenum foil layers 122 used in the method 300 may have a sufficientmolybdenum thermal conductivity 130 (see FIG. 4) to enable themolybdenum foil layers 122 to act as thermal and temperature controllers226 (see FIG. 13) improving a cure cycle, such as improving cure cyclecharacteristics, of the composite structure 104 (see FIG. 4). Asdiscussed in detail above, in another embodiment, the surface treatedmolybdenum foil layers 122 used in the method 300 may have a sufficientmolybdenum stiffness 124 (see FIG. 4) and a sufficient molybdenumstrength 126 (see FIG. 4) to enable the molybdenum foil layers 122 toact as load dissipation paths 206 (see FIG. 11) improving impactdurability of the composite structure 104 (see FIG. 4).

As discussed in detail above, in another embodiment, the surface treatedmolybdenum foil layers 122 used in the method 300 may have a sufficientmolybdenum stiffness 124 (see FIG. 4) and a sufficient molybdenumstrength 126 (see FIG. 4) to enable the molybdenum foil layers 122 toact as load steering paths 215 (see FIGS. 12A-12B) to steer load 214(see FIGS. 12A-12B) around non-load bearing areas 210 (see FIGS.12A-12B) in the composite structure 104 (see FIGS. 12A-12 b). Asdiscussed in detail above, in another embodiment, the surface treatedmolybdenum foil layers 122 used in the method 300 may have a sufficientmolybdenum stiffness 124 (see FIG. 4) and a sufficient molybdenumstrength 126 (see FIG. 4) to enable the molybdenum foil layers 122 toact as reinforcement elements 236 (see FIGS. 14A-14B) and load drawingpaths 235 (see FIGS. 14A-14B) reinforcing and drawing load 234 (see FIG.14A) away from a repair area 230 (see FIGS. 14A-14B) in the compositestructure 104 (see FIGS. 14A-14B). As discussed in detail above, inanother embodiment, the surface treated molybdenum foil layers 122 usedin the method 300 may have a sufficient molybdenum stiffness 124 (seeFIG. 4) and a sufficient molybdenum strength 126 (see FIG. 4) to enablethe molybdenum foil layers 122 to act as fiber stabilizers 270 (see FIG.18) between a cured composite structure 262 (see FIG. 18) and an uncuredcomposite structure 264 (see FIG. 18).

The method 300 is one embodiment of forming the molybdenum compositehybrid laminate 100 or molybdenum laminate layup 101 disclosed herein.However, the molybdenum composite hybrid laminate 100 or molybdenumlaminate layup 101 may be made by any of a number of methods. In thecase of thermoplastic composites, it is preferred that the laminates areprepared by successively laying down long continuous strips ofthermoplastic resin pre-impregnated fibrous tapes (“prepregs”), by meansof a thermoplastic application head, directly onto the treated outersurface of a foil. By laying down strips of tape side-by-side whileconsolidating these through the application of heat and pressure, acontinuous ply of composite with parallel-oriented fibers is produced.Thereafter, another ply or plies of composite may be laid down on top ofthe first ply, depending upon the properties needed of the laminate. Theply or plies make up a layer of composite. Then, a layer of foil isrolled out over the consolidated composite layer and is bonded, forexample heat-fused, onto the composite. Thereafter, a next layer oforganic composite is formed on top of the metallic foil by laying down aply or plies, as described above. Finally, after laying down thepredetermined number of layers of metallic foil and organic polymericmatrix, an outer layer of metallic foil is applied. The outer layers offoil protect the underlying organic composite of the hybrid laminatesfrom the environment and attack by fluids. Alternative methods offabrication are also useful. For example, all layers of the hybridlaminate may be stacked in an autoclave or press, without prefusion oflayers, and may then be fused under applied heat and pressure into aunitary laminate.

FIG. 20 is a flow diagram illustrating another one of the exemplaryembodiments of a method 400 for monitoring the structural health of acomposite structure 104, (see FIG. 4) such as an aircraft structure 10(see FIG. 1), using molybdenum foil layers 122 (see FIG. 4). The method400 comprises step 402 of treating a surface 125 a or 125 b (see FIG. 6)of each of a plurality of molybdenum foil layers 122. The molybdenumfoil layer 122 is surface treated to improve bonding between themolybdenum foil layer 122 and an adjacent composite material layer 106(see FIG. 4). The surface 125 a or 125 b of the molybdenum foil layer122 may be treated with a surface treatment process comprising sol gelsurface treatment, water based sol gel paint, grit blasting, sanding,sandblasting, solvent wiping, abrading, laser ablation, chemicalcleaning, chemical etching, or another suitable surface treatmentprocess.

The method 300 further comprises step 404 of interweaving the surfacetreated molybdenum foil layers 122 with a plurality of compositematerial layers 106. Preferably, each composite material layer 106comprises a fiber-reinforced polymeric material 108 (see FIGS. 4, 5).The surface treated molybdenum foil layers 122 have a sufficientmolybdenum stiffness 124 (see FIG. 4) to leverage the fiber tensilestrength 116 (see FIG. 4) and the fiber stiffness 118 (see FIG. 4) ofthe off-axis fibers 110 (see FIG. 4) in adjacent composite materiallayers 106 via Poisson's effects in the surface treated molybdenum foillayers 122. The surface treated molybdenum foil layers 122 arepreferably separate from each other and have a sufficient molybdenumelectrical conductivity 128 (see FIG. 4) to enable the surface treatedmolybdenum foil layers 122 to act as an electrical bus 160 (see FIG.16). The molybdenum composite hybrid laminate 100 further comprises aplurality of adhesive layers 134 disposed between and bonding adjacentlayers of the composite material layers 106 and the surface treatedmolybdenum foil layers 122.

The method 400 further comprises step 406 of bonding with an adhesivelayer 134 (see FIG. 16) each of the surface treated molybdenum foillayers 122 to adjacent composite material layers 106 to form themolybdenum composite hybrid laminate 100 having improved yield strength102 (see FIG. 4). The interweaving step 404 and/or bonding step 406 ofthe method 400 may further comprise one or more of compacting,consolidating, and curing the interweaved surface treated molybdenumfoil layers 122 and the composite material layers 106. For example, theconsolidating and curing may be carried out via autoclave processing oranother known process.

The method 400 further comprises step 408 of coupling one or moreelectrical sensor devices 168 (see FIG. 16) to the one or moremolybdenum composite hybrid laminates 100. The method 400 furthercomprises step 410 of driving electrical current 170 (see FIG. 16)through the surface treated molybdenum foil layers 122 with the one ormore electrical sensor devices 168. The method 400 further comprisesstep 412 of monitoring any change in electrical current flow 172 (seeFIG. 16) through the surface treated molybdenum foil layers 122 with theone or more electrical sensor devices 168. The method 400 furthercomprises step 414 of obtaining structural health data 254 (see FIG. 16)of the composite structure 104 via one or more signals 252 (see FIG. 16)from the one or more electrical sensor devices 168. The structuralhealth data 254 may comprise one or more of lightning strike detection,initiation of structural flaws, propagation of structural flaws,potential deterioration, actual deterioration, structural health datadetected via full or partial electrical current interruption, or othersuitable structural health data.

Many modifications and other embodiments of the disclosure will come tomind to one skilled in the art to which this disclosure pertains havingthe benefit of the teachings presented in the foregoing descriptions andthe associated drawings. The embodiments described herein are meant tobe illustrative and are not intended to be limiting or exhaustive.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

What is claimed is:
 1. A molybdenum composite hybrid laminatecomprising: a plurality of composite material layers; a plurality ofsurface treated molybdenum foil layers interweaved between the compositematerial layers; and, a plurality of adhesive layers disposed betweenand bonding adjacent layers of the composite material layers and themolybdenum foil layers, wherein each of the plurality of surface treatedmolybdenum foil layers has a sufficient stiffness to leverage a fibertensile strength and a fiber stiffness of off-axis fibers in adjacentcomposite material layers via Poisson's effects in each of the pluralityof surface treated molybdenum foil layers.
 2. The laminate of claim 1,wherein the composite material layer comprises a fiber-reinforcedpolymeric material.
 3. The laminate of claim 1, wherein the laminate isused in a composite structure and improves yield strength in thecomposite structure.
 4. The laminate of claim 3, wherein the compositestructure comprises an aircraft composite structure.
 5. The laminate ofclaim 4, wherein the molybdenum foil layers have a sufficient strength,a sufficient stiffness, and a sufficient electrical conductivity toenable the molybdenum foil layers to act as an aircraft keel beam and acurrent return path for dispersing electrical current from a lightningstrike to the aircraft composite structure.
 6. The laminate of claim 1,wherein the molybdenum foil layer is surface treated to improve bondingbetween the molybdenum foil layer and an adjacent composite materiallayer.
 7. The laminate of claim 1, wherein the molybdenum foil layer issurface treated via one or more surface treatments selected from thegroup comprising sol gel surface treatment, water based sol gel paint,grit blasting, sanding, sandblasting, solvent wiping, abrading, chemicalcleaning, laser ablation, and chemical etching.
 8. The laminate of claim1, wherein two or more of the composite material layers each have acutout portion of surface treated molybdenum foil, and the cutoutportions have interior edges that are staggered to prevent an overlay oftwo or more interior edges in order to provide improved loaddistribution.
 9. The laminate of claim 1, wherein the molybdenum foillayers have a sufficient electrical conductivity to enable themolybdenum foil layers to act as an electrical bus for a compositeaircraft structure.
 10. The laminate of claim 1, wherein the laminate iscoupled to one or more electrical sensor devices that drive electricalcurrent through the molybdenum foil layers and that monitor any changesin flow of the electrical current through the molybdenum foil layers inorder to obtain structural health data of a composite structure.
 11. Thelaminate of claim 1, wherein the molybdenum foil layers have asufficient electrical conductivity and a sufficient thermal conductivityto enable the molybdenum foil layers to act as electrical energydissipation paths improving lightning attenuation of a compositestructure.
 12. The laminate of claim 1, wherein the molybdenum foillayers have a sufficient melting point and a sufficient thermalconductivity that enable the molybdenum foil layers to act as thermalpenetration barriers and thermal energy dissipation paths improvingthermal impingement resistance of a composite structure.
 13. Thelaminate of claim 1, wherein the molybdenum foil layers have asufficient thermal conductivity to enable the molybdenum foil layers toact as thermal and temperature controllers improving a cure cycle of acomposite structure.
 14. The laminate of claim 1, wherein the molybdenumfoil layers have a sufficient stiffness and a sufficient strength toenable the molybdenum foil layers to act as load dissipation pathsimproving impact durability of a composite structure.
 15. The laminateof claim 1, wherein the molybdenum foil layers have a sufficientstiffness and a sufficient strength to enable the molybdenum foil layersto act as load steering paths steering load around non-load bearingareas in a composite structure.
 16. The laminate of claim 1, wherein themolybdenum foil layers have a sufficient stiffness and a sufficientstrength to enable the molybdenum foil layers to act as reinforcementelements and load drawing paths to reinforce and draw load away from arepair area in a composite structure.
 17. The laminate of claim 1,wherein the molybdenum foil layers have a sufficient stiffness and asufficient strength to enable the molybdenum foil layers to act as fiberstabilizers mitigating fiber distortion in a composite structure.
 18. Amolybdenum laminate lay up comprising: a plurality of composite materiallayers; a plurality of molybdenum foil containing layers interweavedbetween the composite material layers, each molybdenum foil containinglayer comprising a composite material layer having a cutout portion of asurface treated molybdenum foil; and, a plurality of adhesive layersdisposed between and bonding adjacent layers of the composite materiallayers and the molybdenum foil containing layers, wherein the surfacetreated molybdenum foil has a sufficient stiffness to leverage a fibertensile strength and a fiber stiffness of off-axis fibers in adjacentcomposite material layers via Poisson's effects in the surface treatedmolybdenum foil.
 19. The molybdenum laminate lay up of claim 18, whereinthe plurality of molybdenum foil containing layers have cutout portionswith interior edges that are staggered to prevent an overlay of two ormore interior edges in order to provide improved load distribution bythe molybdenum foil.
 20. The molybdenum laminate lay up of claim 18,further comprising one or more surface treated molybdenum foil layersadjacent one or more of the composite material layers and molybdenumfoil containing layers.
 21. The molybdenum laminate lay up of claim 18,wherein no adjacent composite material layer and molybdenum foilcontaining layer are orientated at a same angle.
 22. A system formonitoring structural health of a composite structure, the systemcomprising: a composite structure comprising one or more molybdenumcomposite hybrid laminates, each laminate comprising: a plurality ofcomposite material layers; a plurality of surface treated molybdenumfoil layers interweaved between the composite material layers; and, aplurality of adhesive layers disposed between and bonding adjacentlayers of the composite material layers and the molybdenum foil layers,and, one or more electrical sensor devices coupled to the one or morelaminates, the sensor devices driving electrical current through themolybdenum foil layers and monitoring any changes in flow of theelectrical current through the molybdenum foil layers in order to obtainstructural health data of the composite structure via one or moresignals from the one or more sensor devices.
 23. The system of claim 22,wherein the molybdenum foil layers have a sufficient stiffness toleverage a fiber tensile strength and a fiber stiffness of off-axisfibers in adjacent composite material layers via Poisson's effects inthe molybdenum foil layers, the molybdenum foil layers being separatefrom each other and further having a sufficient electrical conductivityto enable the molybdenum foil layers to act as an electrical bus. 24.The system of claim 22, wherein the structural health data is selectedfrom the group comprising one or more of lightning strike detection,initiation of structural flaws, propagation of structural flaws,potential deterioration, actual deterioration, and structural healthdata detected via full or partial electrical current interruption. 25.The system of claim 22, wherein the composite structure comprises anaircraft structure.